I was playing a game as the sith to try out the mod and got gifted general grevious by a City State before i could finish making Darth Maul. This made me unable to make Maul so i had to delete Grevious. I suggest adding a building or wonder (with high production/maintanance cost) that allows 1 additional Jedi Guard type unit, but doesn't allow 2 of the same (allows 1 grevious and 1 maul, but not 2 maul).