The AI seems to be struggerling to grow.

Difficulty Challenging.  Custom soverign (Ceresa variant). 3 AI opponents. Small map, rest of setting were default.

First encountered Magnar, so declared war and easily took his two cities.  Next encountered Porcipinee, declared war and took her 3 cities. Then consolidated and quested. Then went hunting for Relias as he had not shown up.

Found a large undeveloped area east of my border and started grabbing shards and established a new settlement with plenty of more sites available.  In the lower right corner I found 2 Relias towns that easily fell after I declared war. I eventually found Relias wandering in the wilds and finished him off. Considering Relias had been left alone all game the AI had failed to expanded at all after establishing a second settlement. Something seems broken to me.