Focusing on foreign "TikTok refugees" who relocated to RedNote (Xiaohongshu) amid U.S. TikTok policy disruptions, this study addresses a gap in existing research—scholarship on digital migration has largely overlooked language as a strategic resource in abrupt cross-cultural platform shifts, while translingual practice studies often adopt a deficit-oriented lens. Employing qualitative discourse analysis integrated with Communication Accommodation Theory (CAT), Identity Construction Theory (ICT), and translingual perspectives, we analyzed 127 original posts, interactional comments, and 21 semi-structured interviews with purposively selected participants. The analysis reveals that language accommodation on RedNote is a strategic, platform-oriented practice shaped by algorithmic visibility and affective community norms rather than linear convergence or divergence, with users deploying lexical/stylistic convergence, code-mixing, and multimodal translingual practice to construct layered identities such as cultural mediators. Moreover, language adaptation and identity construction form a recursive, co-constitutive dynamic co-shaped by audience feedback and platform ecology. This study contributes to digital communication research by extending CAT to human-platform power relations, reframing translingual practice as agentive identity work, and offering empirical evidence from a non-Western context to challenge Anglocentric biases through a platform-culture dual adaptation model.