Mosaic is clearly a broken mechanic. Anything changing other mechanics of the game to fix this new runeword may likely shape the game around a skewed dynamic.
What about this for Mosaic: Instead of the whole % chance of not using a charge, that instead when you attack or use a skill a random 1-2 charges is applied for the skills you have available or specced into? Or something along these lines, as it would also match the essence of mosaic building up a plethora of charges that look pretty. It would also get rid of the whole having to pre stack charges everytime u do something outside of town