Who suggested emperor? I've only tested on Deity but I don't think difficulty would have such an impact on economy...I started a new game on Emperor as I was suggested and I'm quite frustrated how I can spam as much cities as I want even before Sed. Lifestyle! The maintenance drops from +10 to -16 when I found a new one, but by the time the next Tribe can found a city it's at +10 again.
I'm not using your modmod, did you increase the maintenance here?
What civics were you running? In my test games both me and the 12 other AI only have 3-4 cities when we usually (without the modmod have about 6-12)
This modmod is not finished by far.