I'll speak on what I know first. Yes, just do some random matches, try to make some 5 star bangers out of them and the game will reward you with in game currency. Exhibition and Univers (maybe even GM mode, jeez I haven't noticed smh) reward them. I'm going to go ahead and get the season pass so I stopped going this route...but I was able to unlock several classics stars with in game currency maybe playing 50 various matches with the AI or my kids.
Now take the next part with a grain of salt since I'm not a big CAW user. Maybe someone will come along and confirm.
Main issue in 2K22 was heavy use of CAWs and other custom options (images, etc) caused loss of saves in Universe Mode. I'm hearing it might still be an issue in 2K23.
Again, grain of salt; one that might be new to 2K23 is that CAWs are bugging shows in Universe Mode. The AI doesn't know how to book them for one and the other is if for some reason you delete a CAW from a show, they don't leave the show. That one worries me since I've found some good "starter" CAWs of Superstars from 2K22 that didn't make into 2K23 (ie Mia Yim); as the game gains more of a foothold, naturally, some talented small time (maybe even one time) creators may improve on the starter. Well apparently, I'd have two Mias on RAW unless I deleted the whole show.
FWIW: I used maybe 10 CAWs and their associated images etc. last year and didn't lose any saves. I've only downloaded one so far for 2K23 and I didn't used them outside of exhibition. I ended up deleting it since I wasn't all that impressed with the anything beyond the accuracy of their looks and other than getting a weird prompt after deleting it, no issues. I have two original CAWs I created for MyRise too but that's the only place I use them.
Anyway. Glad you're enjoying 2K23. Sure, game is far from perfect and that causes some toxic nonsense in some online communities...but man ignore that and let yourself get sucked into the fun to be had. I've got a Universe mode planned out for an entire in-game year, MyGM can be fun and I'm enjoying the stories and my CAWs for MyRise.