Algor, Achievements in endgame games on XL/XG maps lose relevance, it's only active at the beginning of the game, but in the end you are so strong that it will not take you any time to have all the combat and collection type ranks to the maximum.
A question that I never knew if it is true, AI also has achievements? An AI that benefits from those achievements faster than you would be an excellent and competent challenge for the mod.