the choice of a CNN makes more sense if you think of a color palette as an extremely low-resolution image rather than a basket of colors.

positioning in a palette matters because colors are perceived relatively.

But all of this can be easily modeled statically and has been. If you desire randomized results, consult a PRNG. This is more, "ML is really cool, what can we apply it to," than "ML provides a better solution to this problem." IMHO.