I've never tried it for audiobooks frankly didn't even know it supported them.
> Let me provide a per-folder template for extracting season / episode information.
That's frankly not what I would call a bug and a bunch of work for near zero benefit. Not to be mean but why do you care? and if it really bothers you just use hardlinks let jellyfin see what it needs and you can have your pretty version for youself.
> I've never tried it for audiobooks frankly didn't even know it supported them.
It's a music player. How could it not support audiobooks? You think it will rate your tracks and refuse to play them if they're insufficiently "musical"?
I really dislike this paradigm that the user needs to become a human DBMS, and rename/link files or write template rules for the media server to understand. It was understandable back in XBMC days but it just feels silly now. Surely it can extract some Musicbrainz-like fingerprint from the media instead of only relying on filename.
But the truly disgusting part is how XBMC/Kodi/Plex/Jellyfin just reassigns the files to another show and there is absolutely no way to audit what's going on other than realizing that some show has two files per episodes or some show you don't have is in the library. Why can't this be easier to inspect?
After two decades I just gave up and use the Home Video mode (just show me my directories mode) on Jellyfin to avoid having to deal with metadata.