I have read several posts where people have discussed adding more than eight civilizations. But there is one thing everyone overlooked - flag colors.
Did you guys add a new flag color graphic for each additional civilization you added? Like, adding yellow, gray, blue-green, and other flags? Otherwise, how would their stats show up on the ranking graphs in the game?
If you look at the alexander scenario then you'll see there are 32 civs in that. Each civ has it's own colour e.g. one might be pink then another lighter pink. It would get confusing if my computer was fast enough to run 32 civs