About Assamese transcription
Assamese (অসমীয়া) is written in Bengali-Assamese and spoken principally in Assam, in north-east India. Subtitles generated here come back in that script, as ordinary written Assamese, ready to use in an SRT or VTT file.
Assamese shares its script with Bengali but adds letters of its own and pronounces several shared ones differently, so picking Bengali for Assamese audio yields text that looks plausible and reads wrong. Select it explicitly rather than relying on detection.

