If I were to edit with isolated audio tracks, might there be a track that is mostly just the music? (I’ve never edited with 5 channel audio so I’m not sure where to even start with that.)
No, it’s all still mixed. Each channel will have sound effects and music in it, except sometimes the center channel will be clean and dialogue-only (though that’s rare).
You might get super lucky and the part you’re looking for will have little/no sound effects in the rear channels, but that’s also very unlikely.