Is Wakanda a Rogue Nation?

The CIA knows that Wakanda has vibranium and lots of it. (That is if Ross decides to tell the USA and his agency.)

The CIA knows that Wakanda has technology and weapons that easily should be considered WMDs. Again depends on Ross.

T'Challa as BP violated the Sokovia accords by operating independently within a sovereign country w/o oversight. But as a King he does have diplomatic immunity.

Wakanda is harboring two individuals who have both violated the Sokovia accords with one both signing and breaking the accords simultaneously. The other (Bucky) is an unregistered weapon and fugitive even though the CIA allowed T'Challa to take him.

I'd say that Wakanda is operating outside the law.