Yes and No. Banks's Culture actively meddles with other races. As I understand it, he didn't like the Prime Directive at all.
He didn't really explore it, though. It was a generic sci-fi setting & basically a backdrop for his "Wakandans turned colonialist as soon as they were cut off from their homeland" idea.
What all of those concepts have in common is: "T'Challa is put in a situation where he's not in control, and is never in control". I mean, look at your examples.:
T'Challa's a bad king because he can't stop corruption.
T'Challa is a bad king because he can't protect his kingdom
T'Challa is a bad king because as soon as his subjects leave his direct control, they turn imperialist. Also, he needs to be nerfed to function on a larger scale.
T'Challa is a bad king because he has spies.
Literally every story we've seen since Coates started is "T'Challa sucks at his job, and needs to be replaced."
And now, what do we have? "T'Challa is such a bad king, there's an entire city that needs protection because Wakanda doesn't have competent law enforcement."
Brand new villains are good. Villains who can threaten him are fine. What I want to see is an arc where T'Challa is COMPETENT. Not a sad sack running around willy-nilly trying to play catch up while his "supporting" cast talks about how bad he is and how bad he should feel about it.
That's called bad writing, my friend.
The funny thing about the Priest era... the era that many (myself included) consider the character's peak? T'Challa usually loses. Oh, he defeats the bad guy eventually, but he ALWAYS has to fight for it. It's just that his plans WORK.
"No outside world stuff" is the problem. There are a lot fewer ways to write internal threats that don't boil down to "Wakanda is just as screwed up as the rest of the world, if not more so." Which is an odd choice to make if you want to "explore Wakanda". As I hinted at above, Ewing's premise STILL makes T'Challa look bad, because apparently the city NAMED AFTER HIS FATHER is in such bad shape, he has to become a vigilante to protect it. It's basically "rape camps" in a less extreme form (I hope). Either it goes to pot REALLY quickly, or the whole thing happened under his watch.
Bottom line: Nobody is saying T'Challa has to be "Catgod" and immediately defeat every threat. But is it too much to ask that we get ONE writer who treats him as someone with a clue?
I know it can be done. Our esteemed Mr. Thorne did it in 22 pages.