I totally second every library enhancements and integrating more tag interpretation. I propably repeat myself, but managing audio files is integrated a bit too rudimentary in Runeaudio. As a work-around I don't use the Library very often and use playlists.
I guess it would be up to those who define the FLAC specifications to tell which tags are standard, as mpd only uses those tags. In addition Runeaudio nevertheless could propably integrate interpreting some more tags. I'd love to see artists sorted without the article, which could be done by a tag within the FLAC files. Or reading a RATING tag for rating information (1 to 5), or...