I primarily listen to classical music on my laptop. Since I'm obsessed with specifics with my music, I am precise with how I label my genres (Opera, Symphony, Chorale, etc.).
Is there a way to edit the Music Lens so that instead of listing "Blues, Classic, Country..." it could list custom parameters?
Could the same be done for the "Decade" parameter? Maybe make it "Century", since I have music from back in the 1400's :)
Currently these can not be edited, your best bet is to file a feature request with the maintainer.
https://launchpad.net/unity-music-lens
Keep in mind that a lense has to be fed by scopes, so not only does the lense need to be updated but whatever scope is feeding it will need some love too. (default is rhythmbox - I think, I use clementine)