@InProceedings{sant-luqueserrano-escolanopeinado:2026:wmt,
  author    = {Sant, Aleix  and  Luque Serrano, Jordi  and  Escolano Peinado, Carlos},
  title     = {Task-Preserving Multilingual Instruction Tuning for Open-Ended QA at WMT 2026 MIST},
  booktitle      = {Proceedings of the Eleventh Conference on Machine Translation},
  month          = {October},
  year           = {2026},
  address        = {Budapest, Hungary},
  publisher      = {Association for Computational Linguistics},
  pages     = {1972--1979},
  abstract  = {We describe our submission to the WMT 2026 Multilingual Instruction Shared Task. We adapt Qwen3-8B with LoRA using organiser-provided data, EuroAlpaca, a multilingual instruction dataset created through task-preserving localisation, and CrossEuroAlpaca, a cross-lingual augmentation that assigns different source and target languages to instructions, contexts and responses. Our system targets open-ended question answering (QA-OEG) in ten shared-task languages represented in the auxiliary data. Under matched decoding, adaptation improves the mean automatic Gemma-4 judge score on target-language QA-OEG by 7.8\% relative to the base model. On the 27-language Aya Evaluation Suite, it yields relative gains of 41.5\% in macro-averaged ROUGE-L and 2.9\% in BERTScore-F1, with larger improvements in the target languages. However, these gains are task- and language-specific. Gemma-4 scores improve for QA-OEG and summarisation in the target languages but decline for context-grounded QA within this set and across all three tasks outside it.},
  url       = {https://aclanthology.org/2026.wmt-1.132}
}