The reason I never did any charts for GH3 is because it was so wonky. I’m not sure if this is how HMX/Neversoft authored the original charts or if the game stored the note data like this internally, but all of the GH3 tools I’ve seen required you to create a MIDI sequence for the played notes. Really odd choice considering the game doesn’t do keysounds or anything like that.
I’m not sure how Clone Hero does it, but I hope that it’s be more sane and accessible.