What really bothers me is the flavor of the Kuriotates. These are supposed to be good guys, but for whatever reason godly folk go to war, they take cities and... millions of people starve to death for no good reason. I don't think the imaginary civ citizens should be listening to news reports of "Good guys invade, tens of millions dead, bodies piled higher than the largest temples"
It frustrates and infuriates me to the point I just really can't play as them.
My suggestion for the Kuriotates is (which solves this from a flavor standpoint):
1. Remove settlements.
2. Whenever a city is captured, its population is transformed into "peasants", who act as slow workers, can be settled as villages, or can be joined into your existing cities. The city itself is abandoned (but doesn't increase the AC).
3. Give the Kuriotates a huge number of special buildings which provide them with resources they don't have. (For example, a Goldsmith might provide them with gold, and a Weaver might give them silk or cotton, the player's choice.) This is very much in-flavor for the cosmopolitan Kuriotate cities.
4. Give the Kuriotates other special buildings that give them bonuses based on what resources they have (i.e. a Jeweler might provide +15% income for each gold, gems and mithril resource they control).
5. Teach the AI to spread its cities further apart. (This is a separate function unrelated to making the Kuriotates playable.)