"People look at what Black did, they see that he didn't adapt many of the banal surface details"
By "banal surface level details" you mean "he made character absolutely nothing like the character in the source material"? Because that's what he did.
"and they take that to mean that he didn't understand or care about the character."
Because he did not. He said he hates the Mandarin as a character. He also called him a communist, which is the same as calling Spider-Man a bad guy. The guy's a hack. If Iron Man 3 didn't prove it, his godawful Predator sequel sure as hell did.
They don't see that he captured the soul of the character
The soul of the Mandarin is displayed in the John Byrne's Iron Man, where Mandarin is shown as a collected, Wuxia-inspired bad guy who is driven by philosophical motives of power and its complete accumulation to build a perfect world. Aldrich Killian was yet another greedy white businessman who wanted to make profit by fooling US government. Been there, done that. Twice.
all while managing to take the racially insensitive and logistically difficult aspects of the character
Pretty much stripping character from anything that makes him a character. And I'm not sure this BS talk about "racially insensitive" has any meaning after MCU released a Spider-Man movie where an underage girl makes a joke about wanting to have sex with an adult man. A joke that was written by middle-aged man who thought it would be funny. If you people can stomach that, I'm sure Mandarin's so-called "racial insensitivity" won't be a big problem for that. I sure as hell am more comfortable with the Mandarin the way he is in the comics than with a bunch of hack writers thinking pedo jokes are super funny. (Hi there, James Gunn.)
and turning them on their head into narrative strengths that were woven into a coherent and effective story.
Hardly coherent when the entire point behind that so-called story relies on its main character being an utter moron, because the film wouldn't even happen if Tony Stark acted like a logical person and didn't ask bad guys to come and bomb his house without trying to create any defense tactics for that, despite him having an army of hyper-advanced, self-controlled suits under his house.
That's just about as good as movie adaptations of things get.
If you are willing to accept any terrible change the MCU does to the source material just because of its brand name, maybe. To the rest of the comic fans, who are not brand followers, I'm afraid we do not share this sentiment.