Junyu Lin
Author directory2026
Q-Align: Query-Boundary Multilingual Alignment for LLM Safety Guardrails
Jiaqi Weng | Meizhen Liu | Xu Guo | Junyu Lin | Jinfeng Li | Jialing Tao | YueFeng Chen | Hui Xue
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Jiaqi Weng | Meizhen Liu | Xu Guo | Junyu Lin | Jinfeng Li | Jialing Tao | YueFeng Chen | Hui Xue
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Multilingual safety guardrails are essential for deployed LLMs, yet they perform poorly on low-resource languages. Prior work typically relies on large-scale multilingual safety data synthesis, which incurs substantial training costs. Cross-lingual transfer offers a cheaper alternative using limited parallel data, and recent work shows that aligning only last-token hidden states can improve multilingual safety. However, although effective for query-only (Q) risk detection, last-token alignment consistently degrades query-response (QR) detection in multilingual settings, limiting its applicability in practical guardrail systems where Q and QR serve as pre-generation and post-generation safety barriers, respectively. In this paper, we propose Q-Align, a method that decouples query intent from response evaluation by aligning only at the query boundary. Specifically, for each parallel sample, Q-Align extracts the hidden state right after the query and aligns multilingual query representations toward a confidence-weighted anchor, allowing languages with stronger intent understanding to guide transfer. We further apply language grouping based on geographic proximity to stabilize cross-lingual alignment. Experiments demonstrate that Q-Align consistently improves multilingual safety detection in both Q and QR scenarios, raising QR average F1 from 74.70% to 80.79% on Polyguard-Qwen, while preserving English performance and generalizing to languages unseen during training.