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Main Authors: Taguchi, Chihiro, Mai, Seng, Kurabe, Keita, Sakai, Yusuke, Agyei, Georgina, Eslami, Soudabeh, Chiang, David
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2508.20511
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author Taguchi, Chihiro
Mai, Seng
Kurabe, Keita
Sakai, Yusuke
Agyei, Georgina
Eslami, Soudabeh
Chiang, David
author_facet Taguchi, Chihiro
Mai, Seng
Kurabe, Keita
Sakai, Yusuke
Agyei, Georgina
Eslami, Soudabeh
Chiang, David
contents Multilingual machine translation (MT) benchmarks play a central role in evaluating the capabilities of modern MT systems. Among them, the FLORES+ benchmark is widely used, offering English-to-many translation data for over 200 languages, curated with strict quality control protocols. However, we study data in four languages (Asante Twi, Japanese, Jinghpaw, and South Azerbaijani) and uncover critical shortcomings in the benchmark's suitability for truly multilingual evaluation. Human assessments reveal that many translations fall below the claimed 90% quality standard, and the annotators report that source sentences are often too domain-specific and culturally biased toward the English-speaking world. We further demonstrate that simple heuristics, such as copying named entities, can yield non-trivial BLEU scores, suggesting vulnerabilities in the evaluation protocol. Notably, we show that MT models trained on high-quality, naturalistic data perform poorly on FLORES+ while achieving significant gains on our domain-relevant evaluation set. Based on these findings, we advocate for multilingual MT benchmarks that use domain-general and culturally neutral source texts rely less on named entities, in order to better reflect real-world translation challenges.
format Preprint
id arxiv_https___arxiv_org_abs_2508_20511
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Languages Still Left Behind: Toward a Better Multilingual Machine Translation Benchmark
Taguchi, Chihiro
Mai, Seng
Kurabe, Keita
Sakai, Yusuke
Agyei, Georgina
Eslami, Soudabeh
Chiang, David
Computation and Language
Artificial Intelligence
Multilingual machine translation (MT) benchmarks play a central role in evaluating the capabilities of modern MT systems. Among them, the FLORES+ benchmark is widely used, offering English-to-many translation data for over 200 languages, curated with strict quality control protocols. However, we study data in four languages (Asante Twi, Japanese, Jinghpaw, and South Azerbaijani) and uncover critical shortcomings in the benchmark's suitability for truly multilingual evaluation. Human assessments reveal that many translations fall below the claimed 90% quality standard, and the annotators report that source sentences are often too domain-specific and culturally biased toward the English-speaking world. We further demonstrate that simple heuristics, such as copying named entities, can yield non-trivial BLEU scores, suggesting vulnerabilities in the evaluation protocol. Notably, we show that MT models trained on high-quality, naturalistic data perform poorly on FLORES+ while achieving significant gains on our domain-relevant evaluation set. Based on these findings, we advocate for multilingual MT benchmarks that use domain-general and culturally neutral source texts rely less on named entities, in order to better reflect real-world translation challenges.
title Languages Still Left Behind: Toward a Better Multilingual Machine Translation Benchmark
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2508.20511