Subtitle settings per library

There’s already an existing feature suggestion discussing the option to set a different language preference for tracks (audio/subtitles) per library. I suggest you comment/vote in that thread in order to avoid distracting or cannibalizing votes.

Similarly there’s a suggestion to set the subtitle for an entire series (or subset) of episodes.

Unless I’ve missed some unique aspect of your suggestion I’m going to close this thread as a duplicate.