I read the book today. Here's what I posted in the spoiler thread.
spoilers:end of spoilers
I though the issue was pretty good overall. I agree that the Avengers should have never been brought up as suspects, Cap wouldn't allow something like that to happen. He would confront T'Challa directly.
I know some people brought up the idea of OC's talking to T'Challa with disrespect. The only thing I can think of these agents have been embedded for so long and indoctrinated in other cultures that they feel emboldened when T'Challa says time to come home. I'd also like to know how much contact T'Challa has had with these agents. If they didn't talk with him on a regular basis, maybe they felt neglected.