With king's favor cards with conversion actions on them, are you allowed to perform those actions an unlimited number of times? For example, there is one that allows you to convert a coin into a cube of any color and vice-versa. Can you do this any number of times up to the amount of money/cubes you have when taking this action?
An conversion ability allows you only one use, unless a little "x2" is added.
Also, while I'm thinking about it, the "cube of any color" icon actually only shows 3 of the 4 colors. Does this icon, in fact, mean a cube of any color or is it only a cube of one of those 3 colors?
It is a cube of any color. I guess it is a weird design choice to only show 3.