Yeah, i'm still looking into 12 TPY, but i have no idea what to do with generic AI incomes and how to set monthly incomes to be relevant, keeping those of 4TPY is just no-go, that is too much, lowering by /4 is just no-go, as factions won't develop there might be kinda solution to multiple cost of building structures, but there will be still no balance with upkeep costs as increasing them kill any faction. Another thing is how to balance politics, because standard in all 12TPY i saw is that your game is finished at about 1/4 time. So world about 415-420 AD is resolved like in 450-455 in 4TPY. Actually it seems 4TPY keeps best balance possible and adding WW allows more political options yet being a choice for advanced/hardcore gamers rather.
What i still hate the most are those random war declarations that you can cancel with immediate peace offer + getting money for it. That's the best climate/balance killer made by CA.