United States

Large language models (LLMs) struggle with low-resource polysynthetic languages, yet the nature of their failures remains underexplored. We evaluate GPT-4o-mini, Gemma~3~27B, Llama~3.3~70B, and NLLB-200 on Spanish$\leftrightarrow$Wixárika translation using zero-shot and 5-shot prompting. All systems are unusable, scoring below 3 BLEU and 21 chrF. Qualitative analysis reveals that LLMs largely ignore source content and instead generate fluent hallucinations. Spanish outputs frequently include indigenous cultural stereotypes such as deer, deities, rain dance, and shamans, regardless of the input, while Wixárika outputs are repetitive across different inputs and morphologically implausible. Few-shot prompting yields model-dependent improvements, with Gemma and Llama improving substantially at higher shot counts while GPT-4o-mini remains flat. These results demonstrate that current LLMs are unable to represent polysynthetic morphology and instead default to exoticizing Indigenous culture and identity. We call for the development of inclusive morphological-aware modeling strategies and increased resource creation to ensure that Indigenous languages of the Americas are represented safely and accurately.

ACL 2026

Deer, Deities, and Dancing: Culturally Biased LLM Hallucination in Low-Resource Wixárika Translation

cultural bias

hallucination

wixárika

low-resource languages

machine translation

#### *Message from the General Chair, Aline Villavicencio*
I’m delighted and honoured to welcome you to the 19th Conference of the European Chapter of the Association for Computational Linguistics (EACL 2026), taking place in the beautiful city of Rabat, in Morocco, in March 24-29, 2026. EACL is the flagship European conference of the Association and EACL 2026 proudly continues our field’s tradition of excellence in scholarship, innovation, and inclusivity. I am deeply grateful to the many volunteers whose dedication, generosity, and tireless efforts have made this conference possible.
For the first time EACL is being hosted in the African continent. This is an important milestone for our community, and we are grateful to our Moroccan hosts for enabling this historic moment by bringing this edition of EACL to Rabat. We are also delighted that the Second Arabic NLP School is co-located with EACL. We hope attendees enjoy this wonderful opportunity to strengthen ties with the Computational Linguistics communities across the African continent. *[Read full message](https://drive.google.com/file/d/14NlmHvwM6fPJuMmOvVh7K0vtQbEyv3SZ/view?usp=sharing)*<br><br>

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EACL 2026

Welcome to the 19th Conference of the European Chapter of the Association for Computational Linguistics (EACL). EACL 2026 will be held in Rabat, Morocco, from March 24–29, 2026. 

workshop paper

It is my great pleasure and honor to welcome you to the 64th Annual Meeting of the Association for Computational Linguistics (ACL 2026), held in San Diego, California, USA, July 2–7, 2026. ACL 2026 continues our fields tradition of excellence in scholarship, innovation, and inclusivity, and I am deeply grateful to the many volunteers who have worked tirelessly to bring this event to life.

It is exciting to see the many developments in the field reflected at our conference, such as the advancement of large language models (born out of our community) into many application directions. This is not without challenges, partly due to unsolved problems, and partly due to misuse of the technology. All this is reflected well at ACL 2026. The conference also reflects that the field is not only about advancing technology, but also the science of fundamentally understanding language and how it is use by many different speaker communities. <br>
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The 64th Annual Meeting of the Association for Computational Linguistics (ACL 2026) will take place in San Diego, California, from July 2 - 7, 2026.

This paper presents IndigiEval, a framework for evaluating the language and cultural proficiency of several commercially available large language models (LLMs) across five North American Indigenous languages (Mvskoke, Choctaw, Cherokee, Cheyenne, and Hawaiian). This framework is a qualitative evaluation method intended for communities with small speaker populations to be able to critically evaluate LLM performance with minimal data and human effort. IndigiEval includes tasks such as answering cultural questions, translation, text generation, and speech recognition. The results of our experiments indicate that no currently available LLM performs well across all evaluation categories, and that LLMs frequently hallucinate orthographies, grammatical structures, cultural knowledge, and vocabulary for all languages and cultures considered. Our proposed evaluation framework is not intended as a comprehensive score, but rather a qualitative and flexible framework to inform language communities about a given LLM's potential as a resource, since each language has unique environments, strengths, and availability of resources.

IndigiEval: Evaluating LLMs in North American Indigenous Languages

This paper presents a study focused on advancing Automatic Speech Recognition (ASR) for the under-resourced language Dënë Sųłıné through data-centric approaches. We explore multiple strategies to enhance the quality of training data—both audio recordings and transcriptions—to address the challenges posed by mixed-quality datasets. Our experiments investigate which data preparation techniques most effectively improve ASR performance in this context. Our findings show that reducing non-phonemic spelling variation in the corpus significantly improves model generalization, resulting in a substantial increase in recognition accuracy. Additionally, we demonstrate that increasing manually reviewed transcriptions consistently improves word and character error rates, while audio enhancement slightly reduces performance, highlighting the complex trade-offs in low-resource ASR development.

A data-centric approach to performance improvement in under-resourced ASR: The case of Dënë Sųłıné

This paper describes ongoing work to develop a corpus of Cahuilla language from the John Peabody Harrington collection, which contains linguistic and ethnographic fieldnotes documenting Indigenous languages of California and other regions across the Americas. Handwritten notes present numerous processing challenges, including scratch-outs, multilingual entries in Spanish and other Indigenous languages, unique abbreviations, and varying script orientations. We compare the efficacy of deep learning text recognition models to convert images of the notes into a machine-readable format, with a focus on respecting tribal data sovereignty in our methods. We find that Pylaia is the most accurate model for our data. Finally, we present the preliminary findings and indicate future directions for developing a Cahuilla corpus.

Towards a Community-accessible Cahuilla corpus: Developing HTR for J.P. Harrington's handwritten fieldnotes on Mountain Cahuilla

In this paper, we aim to answer the following question: could corpus duplication be useful in Natural Language Processing (NLP) for low-resource languages? In these languages (or pi-languages), corpora available for training Large Language Models are virtually non-existent. Specifically, we study the impact of corpus expansion in Nahuatl, an agglutinative and polysynthetic Amerindian pi-language characterised by extensive dialectal variation. Our goal is to increase the size of Nahuatl corpora, which currently consist of a limited number of tokens, through controlled duplication techniques. Our experimental setup employs incremental duplication alongside appropriate corpus balancing, with the objective of training embeddings optimised for downstream NLP tasks. Consequently, static embeddings were trained and evaluated on a sentence-level semantic similarity task. Our results show a significant improvement in performance when incremental duplication is applied, compared to results obtained without corpus expansion. To our knowledge, this technique has not yet been explored in this field.

Corpora duplication for NLP in low-resource languages: A case study of Nahuatl

We present a morphosyntactically controlled transformation dataset for Quechua Collao and evaluate large language models on a sentence-level transformation task under varying prompting conditions. Results show that performance depends on the interaction between model behavior, context size, and linguistic complexity, with smaller models benefiting more from additional examples and morphological hints providing selective gains.

On the Robustness of Morphosyntactic Transformation with Large Language Models: The Case of Quechua Collao

The preservation of under-resourced languages requires digital tools and resources shaped by and for their speakers. We present the first dedicated ASR resources for Puno Quechua (ISO 639-3: qxp): (1) the largest speech corpus for any single Quechua variety, consisting in 66 hours of recordings for scripted and spontaneous speech (including 36 hours of manually transcribed and validated data), collected via a participatory design campaign; (2) the first systematic ASR benchmark for Puno Quechua, evaluating state-of-the-art models and fine-tuning Whisper-base, wav2vec2-base, and XLS-R-300M, with and without continued pre-training (CPT); (3) an open release of all datasets and fine-tuned models.

Building Community-Centred NLP Resources for Puno Quechua

In the context of real-world language technology applications, the language or variety in which a given text is written is often unknown or uncertain. Yet, this information is crucial in order to adequately select and apply appropriate models or resources. Language identification (LID), or the process of determining the language or variety of a text sample, is thus often an important fundamental task in natural language processing. LID can be particularly challenging when: (1) there are not many labeled texts for training; and (2) similar or related languages are involved, since these may share a number of surface-level features. In this paper, we present an LID system for Nahuatl, a group of closely-related language varieties spoken in Mexico and Central America. Nahuatl LID involves both of the aforementioned challenges: Nahuatl varieties can be quite similar, sharing morphemes and even many lexical items, and there is a relative paucity of representative, variant-labeled Nahuatl text. We describe LID experiments for a total of 11 Nahuatl varieties, achieving generally good results (90.59% ±0.09% in 5-fold cross-validation experiments). Many of the outstanding errors are the result of confusion between three highly similar Huasteca variants.

The Power of Simplicity: N-Grams and Transformers in Nahuatl Language Identification

The term "low-resource" is used pervasively in NLP but communicates almost nothing precise. We propose RAN (Resource Abundance Notation), a compact, multi-dimensional notation for quantifying a language's NLP resource profile. A RAN score is written as S/M/L_1-B_1/L_2-B_2/..., where S = floor(log10(speakers)), M = floor(log10(monolingual sentences)), and each L_i-B_i pair records a bilingual partner and floor(log10(parallel sentences)). Values derive from canonical sources: Wikidata for speakers, OSCAR 23.01 for monolingual corpora, and (where available) OPUS for parallel corpora. We score 20 typologically diverse languages and correlate each profile against published benchmarks for three tasks: machine translation (MT, via NLLB-200 chrF++), named entity recognition (NER, via XTREME XLM-R WikiANN F1), and part-of-speech tagging (POS, via XTREME XLM-R UD accuracy). The RAN components carry complementary information: a linear model using all three explains 52% of MT variance, 76% of NER variance, and 72% of POS variance. Among single predictors, B_max (the largest bilingual corpus, regardless of partner) is strongest for the cross-lingual transfer tasks (NER, POS), while M and B_en are strongest for MT. RAN is designed first as a communication tool, not a predictive model.

RAN: Resource Abundance Notation for Languages in NLP

For Mapudungun arn→es translation, morphology-aware tokenization can substitute for a 5× increase in model parameters. We fine-tune three sizes of Meta's NLLB-200 on Mapudungun–Spanish translation across eight tokenization strategies, including our novel Morfessor-VC method, which
constrains Morfessor morpheme segmentation to tokens already present in NLLB's pretrained
vocabulary. Our 600M Morfessor-VC model is competitive with our own fine-tuned 3.3B Standard BPE model on arn→es (43.2 vs. 42.9 chrF++, ∆ = +0.3, p = 0.039, 95% CI [0.02, 0.60]) while using five times fewer parameters, and all fine-tuned conditions surpass frontier LLMs by over 27 chrF++. Mapudungun is an indigenous polysynthetic language spoken by 200,000+ Mapuche people in Chile and Argentina, absent from NLLB-200 and not supported by major commercial MT providers; prior work predates large-scale multilingual models and does not address the tokenization challenges posed by its agglutinative
morphology. These results establish new state-of-the-art baselines for Mapudungun MT and provide a practical foundation for community language tools in pedagogy, social media, and language revitalization.

Bringing Mapudungun into the Modern MT Ecosystem: Morphology-Aware Tokenization for NLLB-200 Fine-Tuning

Qom, a language of the Guaycuruan family, is a low-resource language for NLP and speech processing. We present the first parallel Qom–Spanish corpus in a computationally usable format, comprising 33,392 parallel segments, totaling 1,469,905 Qom tokens and 891,344 Spanish tokens. A subset of 2,943 segments excludes Bible-derived content. It includes alignments at different levels: sentences, sentence fragments, and paragraphs, and is compiled from multiple sources, both previously available and newly collected. 
We also present bidirectional neural machine translation baselines based on NLLB-200, achieving competitive performance in both translation directions on the full dataset, and lower performance on the non-Bible subset. An ablation study shows that training exclusively on biblical data reduces performance on non-biblical text, highlighting the importance of domain diversity in low-resource machine translation.

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