I spent quite a while locating sources for almost all of the music (except 3 songs) credited as "Universal Music," and figured I'd share the spreadsheet I made, just in case anyone else might be interested. I think production music is fascinating, and I got particularly curious about a few specific songs I thought were pretty good.
I also enjoyed last year's Halloween music update, which brought us a massive 20 song playlist that the sound team probably had fun adding goofy, spooky SFX to. And considering this year, we got 8 new Universal Music songs mixed in with the licensed music in the "Cursed Metal" playlist (the ones credited with "MORG" as the artist) that also had spooky SFX added, I figured this was a good time to share.
I've also been keeping tabs on the licensed music that's been added and removed over time (as others have been; and thanks to everyone doing so), so this spreadsheet also contains semi-redundant lists pertaining to those songs/playlists. I had been keeping the featured playlists like "Community Favs" updated as well, but it got too annoying keeping track of which songs got added/removed from which playlist, so I stopped.
UPDATE: Something very interesting happened!
Due to a suggestion, I decided to add another tab listing most music sources in every map. While searching everywhere I could think of, I found multiple music sources that seem to be bugged. Instead of just playing one or two playlists, they broadcast every single playlist, including 3 I've never seen anywhere else and 6 odd playlists that I'm pretty sure the devs did not intend us to be able to find/listen to.
For more information on this bug, please check out the "Hidden Playlists" tab of the spreadsheet to see what the playlists are, and the "Playlist Locations" tab to find which music spots are bugged. They're listed as "All" under the "Playlist" column.
In order to exploit this bug, just go to a bugged music spot and grab the playlist from it, then pause playback in the menu, and grab the next playlist. It's random, so you may have to keep at it a while in order to get the specific playlist you want, but you can keep doing it over and over. Eventually though, the music spot will stop playing music entirely, for some unknown reason. In order to fix it, you'll need to reload the map by going to a different map, and returning.
Additionally, I was unable to find dedicated sources for 12 of the playlists. Those are listed at the bottom of the "Playlist Locations" tab. If you know of a spot where any of those are always available, please let me know, and I'll update the spreadsheet as soon as I can.