Plex will not recognize embedded audio language

If you changed the language tags of your files, clicking > Analyze inside Plex (for the episode, season, show or library), this will re-load those parameters.

For most users, the auto-selection of audio/subtitle tracks based on the track’s language covers all their use cases. There’s a feature suggestion to allow manually changing the default audio/subtitle tracks for an entire show or to remember the manually set audio/subtitle tracks from the previous episode (if manually changed).