Beyond Surface Form: Probing Script and Discourse-Marker Sensitivity in Marathi LLM Reasoning

Tejas Patil, Barnali Chetia


Abstract
Evaluation of multilingual large language models has expanded rapidly, yet aggregate benchmark scores often conceal how performance shifts once the surface form of a language changes. We examine this question through Marathi discourse relation classification. Five instruction-following models, Llama-3.1-8B, Llama-3.3-70B, Qwen3.6-27B, GPT-OSS-20B, and GPT-OSS-120B, are evaluated on a manually curated Marathi language dataset spanning six discourse relations, two scripts, eighteen domains, and three difficulty levels, producing 2500 model-level predictions. Qwen3.6-27B obtains the highest overall accuracy at 82.4%, followed by GPT-OSS120B at 80.8%. The central finding is a large script effect as mean accuracy falls from 78.1% on Devanagari script to 49.7% on Romanized Marathi, a decline of 28.5 percentage for content that is otherwise unchanged. Relationlevel results trace to marker form rather than presence; every instance carries an explicit marker, but Temporal and Contrastive relations use a single canonical connective and are handled reliably, while Inferential and Reformulative relations lean on multi-word phrasal markers and are frequently confused with Causal, a 20.4-point accuracy gap that holds across all five models. Llama-3.1-8B shows a more severe failure, defaulting to Contrastive across most gold relations. These results indicate that strong multilingual performance on Marathi is neither script-invariant nor uniform across discourse relations.
Anthology ID:
2026.oracle-main.28
Volume:
The Proceedings of the Workshop on Open Reasoning Across Cultures Languages (ORACLE)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Leonardo Ranaldi, Giulia Pucci, Federico Ranaldi, Marco Valentino, Alexandra Birch, Fabio Massimo Zanzotto
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ORACLE | WS
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Publisher:
Association for Computational Linguistics
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Pages:
412–419
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URL:
https://aclanthology.org/2026.oracle-main.28/
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Cite (ACL):
Tejas Patil and Barnali Chetia. 2026. Beyond Surface Form: Probing Script and Discourse-Marker Sensitivity in Marathi LLM Reasoning. In The Proceedings of the Workshop on Open Reasoning Across Cultures Languages (ORACLE), pages 412–419, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Beyond Surface Form: Probing Script and Discourse-Marker Sensitivity in Marathi LLM Reasoning (Patil & Chetia, ORACLE 2026)
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https://aclanthology.org/2026.oracle-main.28.pdf