It should be fine painting over future, in fact some people have used it as a primer (including me).
You can paint over future with acrylics and even laquer paints. I once used future as a barrier between bare plastic and a laquer based primer to keep the primer from eating into the plastic, and it worked great for me, just make sure the future has plenty of time to cure.
If your painting with acrylic over future there shouldn't be a problem as future is an acrylic.