Sounds ridiculous and is most likely a fan rumor more than any studio rumor. Why would you need to tweak Kraven to make him from Wakandan for a Spiderman movie. That's a lot of extra hoops to jump through.
Someone probably took Cooglers' and Watts' interest in using the character and smashed them together. lol
It probably IS a ridiculous rumor, but I actually LIKE the notion of making Kraven Wakandan...despite the immediate death traps of racist stereotypes that spring up IMMEDIATELY with the notion of Kraven being from Wakanda. As many of you know, I really like Kraven and The Taskmaster. I think they're two of the most underused and some of my most favorite "street level" villains...along with my manz Arcade. Yes, Murderworld's Arcade. I have a list of now lesser known villains who have IN-CRED-IBLE potential imo. And anti-heros, sometimes hero/villain types too. Silver Sable is also one of my much slept upon favorites. Like the more villainous Gambit, and a fusion of Ultimate Longshot-Shattershot but minus the psychopathic tendencies. And the more honor flavored but definitely assassin centered Elektra, Bullseye, Boomerang and Silver Samurai. I love me some GORGON, too...the GORGON from The Hand, the Tomi Shishido Gorgon, not The Inhuman Gorgon.

In my fanfic? GORGON works with HELANA DAUGHTER OF HELA. In my fanfic, Hela raped Thor while Thor was passed out from one of his many extraordinary and literally Hel defying adventures...and instead of yielding a son like in The Ultimate Universe, she bore Thor a daughter.
GORGON and HELANA needed zero incentive to attack the group of heroes that BLADE and DR. VOODOO are temporarily aligned with. But I won't spoil more of my fanfic. Just realize? That T'Challa...my nonsuperhuman T'Challa, the OG T'Challa...faced GORGON and HELANA by himself, at some point in my fanfic.