GaelEval: Benchmarking LLM Performance for Scottish Gaelic

Fuente: arXiv
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Autori principali: Devine, Peter, Lamb, William, Alex, Beatrice, Ezeani, Ignatius, Knight, Dawn, Meachair, Mícheál J. Ó, Rayson, Paul, Wynne, Martin
Natura: Preprint
Pubblicazione: 2026
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author Devine, Peter
Lamb, William
Alex, Beatrice
Ezeani, Ignatius
Knight, Dawn
Meachair, Mícheál J. Ó
Rayson, Paul
Wynne, Martin
author_facet Devine, Peter
Lamb, William
Alex, Beatrice
Ezeani, Ignatius
Knight, Dawn
Meachair, Mícheál J. Ó
Rayson, Paul
Wynne, Martin
contents Multilingual large language models (LLMs) often exhibit emergent 'shadow' capabilities in languages without official support, yet their performance on these languages remains uneven and under-measured. This is particularly acute for morphosyntactically rich minority languages such as Scottish Gaelic, where translation benchmarks fail to capture structural competence. We introduce GaelEval, the first multi-dimensional benchmark for Gaelic, comprising: (i) an expert-authored morphosyntactic MCQA task; (ii) a culturally grounded translation benchmark and (iii) a large-scale cultural knowledge Q&A task. Evaluating 19 LLMs against a fluent-speaker human baseline ($n=30$), we find that Gemini 3 Pro Preview achieves $83.3\%$ accuracy on the linguistic task, surpassing the human baseline ($78.1\%$). Proprietary models consistently outperform open-weight systems, and in-language (Gaelic) prompting yields a small but stable advantage (+$2.4\%$). On the cultural task, leading models exceed $90\%$ accuracy, though most systems perform worse under Gaelic prompting and absolute scores are inflated relative to the manual benchmark. Overall, GaelEval reveals that frontier models achieve above-human performance on several dimensions of Gaelic grammar, demonstrates the effect of Gaelic prompting and shows a consistent performance gap favouring proprietary over open-weight models.
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id arxiv_https___arxiv_org_abs_2604_02135
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle GaelEval: Benchmarking LLM Performance for Scottish Gaelic
Devine, Peter
Lamb, William
Alex, Beatrice
Ezeani, Ignatius
Knight, Dawn
Meachair, Mícheál J. Ó
Rayson, Paul
Wynne, Martin
Computation and Language
Multilingual large language models (LLMs) often exhibit emergent 'shadow' capabilities in languages without official support, yet their performance on these languages remains uneven and under-measured. This is particularly acute for morphosyntactically rich minority languages such as Scottish Gaelic, where translation benchmarks fail to capture structural competence. We introduce GaelEval, the first multi-dimensional benchmark for Gaelic, comprising: (i) an expert-authored morphosyntactic MCQA task; (ii) a culturally grounded translation benchmark and (iii) a large-scale cultural knowledge Q&A task. Evaluating 19 LLMs against a fluent-speaker human baseline ($n=30$), we find that Gemini 3 Pro Preview achieves $83.3\%$ accuracy on the linguistic task, surpassing the human baseline ($78.1\%$). Proprietary models consistently outperform open-weight systems, and in-language (Gaelic) prompting yields a small but stable advantage (+$2.4\%$). On the cultural task, leading models exceed $90\%$ accuracy, though most systems perform worse under Gaelic prompting and absolute scores are inflated relative to the manual benchmark. Overall, GaelEval reveals that frontier models achieve above-human performance on several dimensions of Gaelic grammar, demonstrates the effect of Gaelic prompting and shows a consistent performance gap favouring proprietary over open-weight models.
title GaelEval: Benchmarking LLM Performance for Scottish Gaelic
topic Computation and Language
url https://arxiv.org/abs/2604.02135