Hello Spoon,
is there a chance to see a dynamic playlist? It would select & play all songs in the library found by the search criteria like the dynamic browsing. Actually there exists dynamic playlists like 1960s, 1970s, ...
This could be something like: all titles with <<Genre like "Ballad" OR Genre like "Lo-Fi" OR Genre like "Downtempo" AND BPM < 120">> or even more complicated. The selection string should either be entered in an .M3U file or withing the application.
The custom title of these playlist should be displayed beneath other playlists.

Greetings
-Mike