The Devil is in the Details: Assessing the Effects of Machine-Translation on LLM Performance in Domain-Specific Texts

Javier Osorio, Afraa Alshammari, Naif Alatrush, Dagmar Heintze, Amber Converse, Sultan Alsarra, Latifur Khan, Patrick T. Brandt, Vito D’Orazio


Abstract
Conflict scholars increasingly use computational tools to track violence and cooperation at a global scale. To study foreign locations, researchers often use machine translation (MT) tools, but rarely evaluate the quality of the MT output or its effects on Large Language Model (LLM) performance. Using a domain-specific multi-lingual parallel corpus, this study evaluates the quality of several MT tools for text in English, Arabic, and Spanish. Using ConfliBERT, a domain-specific LLM, the study evaluates the effect of MT texts on model performance, and finds that MT texts tend to yield better results than native texts. The MT quality assessment reveals considerable translation-induced distortions, reductions in vocabulary size and text specialization, and changes in syntactical structure. Regression analysis at the sentence-level reveals that such distortions, particularly reductions in general and domain vocabulary rarity, artificially boost LLM performance by simplifying the MT output. This finding cautions researchers and practitioners about uncritically relying on MT tools without considering MT-induced data loss.
Anthology ID:
2025.mtsummit-1.24
Volume:
Proceedings of Machine Translation Summit XX: Volume 1
Month:
June
Year:
2025
Address:
Geneva, Switzerland
Editors:
Pierrette Bouillon, Johanna Gerlach, Sabrina Girletti, Lise Volkart, Raphael Rubino, Rico Sennrich, Ana C. Farinha, Marco Gaido, Joke Daems, Dorothy Kenny, Helena Moniz, Sara Szoc
Venue:
MTSummit
SIG:
Publisher:
European Association for Machine Translation
Note:
Pages:
315–332
Language:
URL:
https://aclanthology.org/2025.mtsummit-1.24/
DOI:
Bibkey:
Cite (ACL):
Javier Osorio, Afraa Alshammari, Naif Alatrush, Dagmar Heintze, Amber Converse, Sultan Alsarra, Latifur Khan, Patrick T. Brandt, and Vito D’Orazio. 2025. The Devil is in the Details: Assessing the Effects of Machine-Translation on LLM Performance in Domain-Specific Texts. In Proceedings of Machine Translation Summit XX: Volume 1, pages 315–332, Geneva, Switzerland. European Association for Machine Translation.
Cite (Informal):
The Devil is in the Details: Assessing the Effects of Machine-Translation on LLM Performance in Domain-Specific Texts (Osorio et al., MTSummit 2025)
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PDF:
https://aclanthology.org/2025.mtsummit-1.24.pdf