not knowledgeable about them things but normal movies and shows with multiple audio streams and subtitles play just fine with directplay, selecting them from the client works fine, etc.
the only reasons I know of for transcoding would be if you have ancient clients that can't play e.g HEVC or something, or if you're on shitty broadband and it ain't feasible to stream 4K to a phone.
I am asking the dude doing the transcoding why he's doing it. I am not waging a crusade against all dudes doing transcodings.
to answer your question, no, I don't, all media I got is 1080p and all my devices can display it.