FWIW, I have done two frames with PC (including a PC clear coat) and then used rattle can clear coat to go over my sensitive water slide decals. I have not had any issues on either bike. I use duplicolor acrylic enamel spray can per Velocals recommendation.
I am not a chemist but since PC is basically just a polymer coating it's pretty non reactive and I don't think the solvents in most paints will do much harm.
...it's not the paint solvents affecting the PC you need to worry about. It's the longer term adhesion of your paint to the very slippery and impervious powdercoated surface. I have painted over powdercoat once or twice. It seems to work fine if you thoroughly rough the surface, and then use a good quality self etching primer. You could probably rough it , then prime it with a 2 part urethane as well (but I've never tried this).
The issues with all painted surfaces that involve multiple coats are mostly about getting the subsequent coats of paint to adhere to whatever is already on there. AS long as whatever is already on there is still solidly attached to the surface. That's why there are things like "recommended recoat windows", that most paint manufacturers supply as part of their instructions for application. Youi can certainly violate those recommendations out of some necessity. I do it because I need to let the wet paint surface of the color coat dry enough that the application of decals/stickers won't lift or damage it.
But you do so at your own risk, and probably ought to experiment on something that's not as important to you when you do so.