CUNI-AR Team at WMT26 General Translation Task for Egyptian Arabic

Josef Jon, Rawan Bondok, Miroslav Hrabal, Ondřej Bojar


Abstract
We describe the Charles University CUNI-AR submission to the WMT26 General Translation shared task for English into Egyptian Arabic. Our pipeline is built around GEMBA (LLM-as-judge quality) estimator that scores translations independently for accuracy and dialect authenticity. We use it throughout our pipeline: to filter training data, to construct preference pairs for DPO, to select best checkpoints, and to pick the best hypothesis per segment at inference time. Our primary translation model is Gemma-4-12B-it finetuned via QLoRA, we also finetune Jais-2-8B-Chat and Aya-expanse-8B. Gemma-4-12B-it provides a high-quality Egyptian Arabic translation, so SFT yields only marginal quality gains in automatic metrics; DPO is able to improve the metrics it optimizes for, but the real gain in translation quality is to be assessed by human evaluation. The final submission selects the best-scoring translation per segment from 31 candidate checkpoints, with the unmodified base model contributing 31\% of the output.
Anthology ID:
2026.wmt-main.68
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:
1271–1283
Language:
URL:
https://aclanthology.org/2026.wmt-main.68/
DOI:
Bibkey:
Cite (ACL):
Josef Jon, Rawan Bondok, Miroslav Hrabal, and Ondřej Bojar. 2026. CUNI-AR Team at WMT26 General Translation Task for Egyptian Arabic. In Proceedings of the Eleventh Conference on Machine Translation, pages 1271–1283, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
CUNI-AR Team at WMT26 General Translation Task for Egyptian Arabic (Jon et al., WMT 2026)
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PDF:
https://aclanthology.org/2026.wmt-main.68.pdf