So I did the "right" thing and actually bought a perpetual license for Studio One 7, and instantly regreted it.

It was, of course a DOWNGRADE. Many of the loops and add-ons only come with the subscription model.

Can I somehow get legit libraries, like Sub Zero Bass or Cinematic Lights to run inside a cracked S1?

I was thinking:
Plan A - use two Studio One instalations - one cracked, one legit. But they probably share registry/program data/app data etc
Plan B - Somehow have the Sphere Manager license be the same with my legit license. Not sure how to do that.

 

Best you can do is to crack your own legit installation... if you have all the files you need, I think the current R2R crack fools Studio One by giving you a fake Sphere license that unlocks everything. But that means you won't have access to the stuff you can do if you're logged in to your account.

My suggestion is to switch back to cracked Studio One and go on buying individual licenses for everything you want from third party stores. Though, if it's the newer stuff, I guess those are locked into the subscription? Can't really tell because I don't use any of the bundled stuff that comes with Studio One, I only have Retro Mix Legends for the SSL Mix FX plugin.