Hi! Unfortunately I’ve pretty much given up on this. OSC works great, but currently the only thing FMOD responds to is direct integration with a game engine. I know you can use the low level API on its own, but it kind of defeats the purpose at that point.
I’ve been finding it easier just to use Unity either as the primary platform, or to use Unity as an OSC Host between Processing and FMOD. You can send OSC messages out of processing however you want, then grab them in unity and have FMOD do whatever you want it to. Let me know if that works!