If possible add a feature to load from the web (musicbrainz DB?) the year for a given track and store the info accordingly. Even more better, if using musicbrainz API, would be to allow the "Original release date" for a given track and store this either in the YEAR tag or in a custom tag.
You should let this tagging feature as Musicbee does currently: allow only replacing of this tag, leaving others untouched.
What do you think?