Here is a quick tip for metacreator Ars Magica users who wish to emulate the character creation rules accurately.
The problem: Metacreator does not handle Affinities for Arts and Abilities in the same manner as the core rulebook mechanics. The difference is minor, but sometimes those points count. It adds a multiplying factor to the spending of XP into the calculations of ability levels, rather than showing the allocated XP and then the updated level after the multiplication.
The fix: is to add generic virtues called Affinities so that the Virtues and Flaws balance, but the XP spend also adds up correctly. The downfall is that you need to roughly know what the score will end up being when you’re done spending XP, but that isn’t a show stopper to get a 100% core rules character.