You've already fixed 2 issues I had already:

1. Higher Garrisons
2. Much lower resettling costs

There's a couple other issues I think can be solved with mods:
1. No barbarian super-alliance - either reduce/limit the stacking +/- modifiers from allies being at war, or change the barbarian factions to start at war with 1 other tribe.
2. AI more willing to trade?
3. "New Kingdom" Is this working properly? It's not clear from the wording if it reduces cost or just time. Even if we assume it just reduces the time, it seems to give at most a 25% reduction in time, not a 50% reduction.