Can you consider implementing Colour [COL] pop-up button menu next to PLAY [in top of each Track] where 6 predefined colour combinations will appear and you will be able to chose one of them for each track or none?
It will help better managing if song have many tracks. See my quick-mosk-up example:
What do you think? This way users who don`t want their music track look like “christmass tree” to leave this colour option to OFF and those who want to add colours [for faster work] will be able to chose one of 6 [or more] colour combinations?