This is true, but only because the samurai, ninja, and knights we have in the game are culturally specific and fit the qualities of their archetype in a clear cut way. If they make a tribal character who, unlike Rock, fits into the rich lore that they’re based in, I’m totally fine with it :)
I think you're both right here, honestly. On the one hand, yes--the design, aesthetic, and provenance of the various clothing, armor, and weaponry used in these games (at least as regards the actually historically-derived stuff) is a mish-mash of elements taken from numerous cultures over spans of literally thousands of years, with a further lion's share being either complete fantasy or historical with a fantasy twist. With regard to just about any character's specific outfit (and for that matter, weapon), when compared against when and where they are said to hail from, said outfit and gear is either anachronistic or not something that would have been traditionally found in their culture at
any point in the historical past. Even those which have the rough shape of traditional clothing from that time and place seem to be using materials, dyes, patterned textiles and armour composition and contours that make no sense if you don't have your "anime exception" goggles on (which you always need when playing Soul Calibur, obviously).
All of that said, there's definitely still a huge potential for problems here with a "tribal African" character, whether the particular garb is historically accurate or not. And that problem is that Japanese media companies, as a class, do not have the best track record of representing black characters with much sensitivity, whether the setting is historical, fantasy, or (as here) a mixture of the two. On the other hand, you also wouldn't expect a Japanese company to make not just one but four of its classic characters Korean, and yet the Seong clan are not only major characters in the narrative, they are actually treated with some reverence and respect within Soul Claibur cannon. Still, when it comes to a black character who's going to be even vaguely situated as connecting to a historical African culture, I think there's real reason to be worried that we might end up with something similar to
this.
On the other hand, Soul Calibur started out a kind of global showcase of historical cultures and weapon arts (highly stylized and fantasy goofball as the representations may be), before taking a hard right turn into full-on fantasy by the time SCIII came about. Personally, I'd welcome a return to that classic formula on new characters being representative of historical real world cultures (especially if the alternative is the likes of Azwel and Groh....), and Africa is at the top of the list of major regions that have zero representation so far. So...if they could thread the needle and make a sensible quasi-historically accurate and respectful design, I'd say an African character would be welcome.