You asked it for a novel musical notation, and it gave you a riff on guitar hero and DDR and beat saber.
Not only that, but it wouldn't really work well for music played by professionals. Putting multiple parts together is reducing how easy it is to distinguish your part, compared to the norm where you JUST have your part, and adding color to the party doesn't get you back that level of being able to distinguish your part, and might even require different parts of your brain get involved.
It sounds exactly like the kind of thing a stoner comes up with and crows about before they sober up and realize "no wait, that wasn't really a good idea and I know nothing about the relevant domain". No wonder these chat bots are so popular on HN