ComplexityMT: Benchmarking the Interaction Between Text Complexity and Machine Translation

Joseph Marvin Imperial, Junhong Liang, Belal Shoer, Abdullah Barayan, Rodrigo Wilkens, Omar Mussa, Dawn Knight, Eugénio Ribeiro, Ekaterina Kochmar, Sowmya Vajjala, Fernando Alva-Manchego, Harish Tayyar Madabushi


Abstract
When a text is translated, does the translation retain the complexity of the original? We introduce ComplexityMT, a new challenge for assessing how text complexity and machine translation interact with and influence each other, using the CEFR levels as the measure of text complexity. Across six languages, including Arabic, Dutch, English, French, Hindi, and Russian, we evaluate three open-weight models, one closed model, and a commercial machine translation system on two tasks: i) correlation of CEFR with translation difficulty, and ii) shifts in CEFR levels of the source texts. Our experiments show that higher CEFR levels make texts more difficult to translate, and that machine translation shifts the CEFR level of the target text compared to the original source, for most languages. These findings provide new insights for researchers and practitioners working on multilingual pedagogical content generation and MT difficulty estimation.
Anthology ID:
2026.findings-emnlp.442
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
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SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
9269–9283
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URL:
https://aclanthology.org/2026.findings-emnlp.442/
DOI:
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Cite (ACL):
Joseph Marvin Imperial, Junhong Liang, Belal Shoer, Abdullah Barayan, Rodrigo Wilkens, Omar Mussa, Dawn Knight, Eugénio Ribeiro, Ekaterina Kochmar, Sowmya Vajjala, Fernando Alva-Manchego, and Harish Tayyar Madabushi. 2026. ComplexityMT: Benchmarking the Interaction Between Text Complexity and Machine Translation. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 9269–9283, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
ComplexityMT: Benchmarking the Interaction Between Text Complexity and Machine Translation (Imperial et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.442.pdf