Lost in Interpretation: The Plausibility-Faithfulness Trade-off in Cross-Lingual Explanations

Somnath Banerjee, Pranav Jha, Rima Hazra, Animesh Mukherjee


Abstract
LLMs deployed multilingually are often audited via English explanations for non-English inputs. We evaluate extractive explanations "where the model identifies input token spans as evidence alongside a generated rationale” and uncover a systematic trade-off: English-pivot explanations can achieve higher span agreement with human rationales while their evidence becomes less causally grounded in the model’s prediction, as measured by both comprehensiveness and sufficiency. Across 3 tasks, 5 languages, and 2 multilingual LLM families, we find that English explanations frequently produce fluent but loosely anchored rationales, with comprehensiveness degrading by up to 5.7x relative to native-language conditions - even as task accuracy remains stable across settings. For socially nuanced classification, English pivots also fail to preserve pragmatic cues, reducing both faithfulness and span agreement. We recommend auditing explanations in the input language, reporting multi-faceted faithfulness metrics beyond lexical overlap, and treating English rationales as communication summaries rather than faithful decision traces.
Anthology ID:
2026.emnlp-main.2289
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
52077–52101
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2289/
DOI:
Bibkey:
Cite (ACL):
Somnath Banerjee, Pranav Jha, Rima Hazra, and Animesh Mukherjee. 2026. Lost in Interpretation: The Plausibility-Faithfulness Trade-off in Cross-Lingual Explanations. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 52077–52101, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Lost in Interpretation: The Plausibility-Faithfulness Trade-off in Cross-Lingual Explanations (Banerjee et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2289.pdf