So this recent patch seems to have fixes the 12/18 stars achievements.  However I'm wondering if I can load up an old game to get them.  Doesn't seem so.  I noticed in my current game I received the Nicola achievement for 12 scientist stars in a game.  So I loaded up an old game - a save where I had 18 Aesthete stars.  It didn't register.  So I'm guessing that the achievement either a) won't work on those old games, or b) only triggers the moment you get that 18th star.  Anyone know for sure before I waste a bunch of time replaying many turns to hit that 18 mark again?

I have a partial answer.  It triggers when you get another star.  So in my reloaded game I had 16 stars.  I started playing and when I got my 17th star it gave me the Sejong achievement for 12 stars.  Not sure if it only calculates when you get an Aesthete star of if any start causes the eval. Guessing it is just within the focus.