The list of tags you provided is what Plex currently supports, and for that reason is the minimal effort someone should put into it. However, in order to be truly useful for all music, but especially for classical music, Plex needs to support several more tags. I wrote a feature request asking Plex to do just that, and Plex’s co-founder recently hinted at upcoming (though that could mean years) improvements in this area. In the feature request you’ll find a list of tags that I feel would allow Plex to manage a well-organized classical library.
My recommendation to the OP, and to anyone with a collection of classical music, is to populate your embedded tags as thoroughly as possible in anticipation of those improvements, and to please add your vote to that feature request, if you haven’t already.
