IFMTBench: A Comprehensive Benchmark for Multilingual Translation Instruction Following

Mingrui Sun, Mao Zheng, Zheng Li, Mingyang Song


Abstract
Modern translation workflows demand more than semantic equivalence. Users routinely require models to preserve JSON or HTML schemas, honor curated glossaries, disambiguate with provided context, and match prescribed registers, often several at once. Conventional metrics such as BLEU and xCOMET capture semantic fidelity but provide little signal on constraint adherence, while general instruction following benchmarks ignore the cross-lingual nature of translation. We introduce IFMTBench, a benchmark for multilingual translation instruction following covering seven high-resource languages, with 4,506 single-constraint and 2,838 multi-constraint items spanning seven constraint dimensions and five compositional patterns with instructions issued in all seven languages. Constraints are split into a gating subset verified by deterministic checkers and a continuous subset scored by a rubric-based LLM judge, combined under a multiplicative rule that resists reward hacking. Evaluating 15 models reveals systematic gaps that prior protocols miss: Instruction following scales with size more sharply than translation quality, glossary and structured-format constraints dominate the difficulty gradient, and general instruction following rankings correlate only weakly with translation behavior. Our benchmark is available at https://github.com/Tencent-Hunyuan/Hy-MT2/tree/main/IFMTBench.
Anthology ID:
2026.findings-emnlp.1016
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
21457–21468
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1016/
DOI:
Bibkey:
Cite (ACL):
Mingrui Sun, Mao Zheng, Zheng Li, and Mingyang Song. 2026. IFMTBench: A Comprehensive Benchmark for Multilingual Translation Instruction Following. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 21457–21468, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
IFMTBench: A Comprehensive Benchmark for Multilingual Translation Instruction Following (Sun et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1016.pdf