Does the game has FORCE DIPLOMACY?

diplomacy in this game is minimal at best.

About the internal politics...
Especially since I still don't know how the thing even worked. There is just no feedback in the game on showing how well or how badly I did diplomatically. Worse, it would call be for nothing once the civil war is triggered as once that happens it all ends.

As for external politics? The game had bugs/incomplete issues that made them unresponsive to your might or threat level at launch, but it seems they finally fixed that.

I'm pretty sure they did that on purpose especially they openly welcome modders and mods

I believe FORCE DIPLOMACY is the solution for stupid AI in regards with diplomacy.

Seasons and other advanced options which make the game interesting are beyond what capabilities of mods. Tweaking startpos for a single integer value isn't much of a mod in my mind, it should just be an ingame option.

Each faction should have at least 1 major bonus and penalty in both military and economical traits.

FYI, Rome 2 is on sale on Steam for 30 bucks (50% off flash sale). Lowest it'll ever be at least until the next Steam sale. You can also pick up the first 2 DLCs for 50% as well; the latest however, is not on sale.