The problem is that you want to play Kongo as rich and stable European country with tons of accepted cultures, troops and money. What's the point of playing Africa then? Can you imagine level of centralisation in tribalistic Africa IIRC? Unrest is much more manageable. Blobbing is easy. Just increase the autonomy, it will fade away. Or play England or France.
Historically, Kongo was a centralized state *in this time period*, even in 1444. And accepted cultures was never the problem. (You have so little basetax that accepting another culture is frequently easy - 20% of 20 is 4, and you don't even start with 20BT, you start with 14 as Kongo).
Gameplay-wise, the RotW didn't need a massive nerf relative to Europe. Plus getting a weak heir is close to game-ending, because rebel stack sizes are out of control for anyone but rich european nations.
What I'd like is to be able to do things and not need to sit with speed 5 (choppily) on for several hours before I can do anything, nor should i be more scared of rebels than any or *all* of my neighbors. It was vastly more interesting to play in the RotW before, despite the reworked patch, because you could actually *play the game*.
I don't need tons of troops or money, I want the game to be playable for nations that don't have tons of troops or money.
The severe nerf to harsh treatment is especially egregious here.
Finally, the lack of decisions for non-Christian, non-Muslim countries is not related to being poor, it's related to being non-Christian and non-Muslim. (Advisors costing the same whether in Europe or far-flung Africa is also kind of non-sensical, but then, the game's handling of wealth is ridiculously bad too).
Oh yeah, and lack of money... the pagan gold-income nerf certainly doesn't help. Something else that doesn't affect europeans or islamic nations...