UniVie-HAITrans at WMT26 Terminology Translation Task: Terminology-Guided Data Filtering and Few-Shot Fine-Tuning for Lightweight LLMs

Miguel Angel Rios Gaona


Abstract
Specialised domain translation using Large Language Models remains challenging due to terminology constraints, scarce in-domain parallel data, and the tendency of fine-tuning to degrade in-context learning performance. We present our submission for the English–Polish and Spanish–Basque translation in the Medical and Engineering & Technology domains. Our method follows three stages: i) We extract in-domain terms from a terminology database and prompt a multilingual LLM to generate contextual sentences for each term. ii) We build an efficient search index over large-scale, unconstrained web-crawled and medical parallel corpora. Using the synthetic sentences as queries, we retrieve and filter the most semantically relevant pairs to build an in-domain fine-tuning dataset. iii) We structure our training instances with a mixture of 0-shot and semantically retrieved 5-shot prompts, and fine-tune lightweight multilingual LLMs (Gemma-3-4B, and Tiny-Aya-Global) via QLoRA. Fine-tuned Gemma-3 achieves the best results on held-out data across all metrics on English–Polish (Medical) and on Spanish–Basque (Engineering & Technology), showing that few-shot fine-tuning enhances specialised domain translation quality and preserves in-context adaptation.
Anthology ID:
2026.wmt-main.122
Volume:
Proceedings of the Eleventh Conference on Machine Translation
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Barry Haddow, Tom Kocmi, Philipp Koehn, Christof Monz
Venues:
WMT | WS
SIG:
SIGMT
Publisher:
Association for Computational Linguistics
Note:
Pages:
1873–1880
Language:
URL:
https://aclanthology.org/2026.wmt-main.122/
DOI:
Bibkey:
Cite (ACL):
Miguel Angel Rios Gaona. 2026. UniVie-HAITrans at WMT26 Terminology Translation Task: Terminology-Guided Data Filtering and Few-Shot Fine-Tuning for Lightweight LLMs. In Proceedings of the Eleventh Conference on Machine Translation, pages 1873–1880, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
UniVie-HAITrans at WMT26 Terminology Translation Task: Terminology-Guided Data Filtering and Few-Shot Fine-Tuning for Lightweight LLMs (Gaona, WMT 2026)
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https://aclanthology.org/2026.wmt-main.122.pdf