I don’t know if it was from a mod, but when I played with a friend there was a modifier to disable failing out of songs, so we’d enable it on those songs and just swing along wildly as best we could, and still finish them. Also helped us get a lot better at the game. Maybe that would work?
SMT negotiations are by far my favorite monster-collecting methods. Just equal parts philosophy, flirtation, and gibberish as they vibe check you.