Aquila SPQR
King
Well... my actual game seem to be... ok. Monarch, but I am able to maintain steady economy and good army. Also in number of cities I'm on the first place. Maybe my previous bad experience with monarch was because of poor starting location and early enemy invasion.
As I said, a higher difficulty level doesn't mean a smarter AI; it just means an AI which has more bonuses in comparison to human players (faster research and unit building, lower inflation, etc).

Which file did you see that change in?