Imagine the rest of the world wake up to see a YouTube video titled
First Look: Mutapa.
As exotic and interesting as it can, I'd argue that will probably leads to the doom of Civilization 6. We have enough backlash already from Georgia. Outside here/reddit, people were disappointed and sarcastically commented "coming up next! First Look: <
some obscure civ (I don't remember too)>", et cetera.
That was Georgia. A real country name (that we learned during school geography), that share a name with modern US state and some European ruler/placenames...
Personally, I've never heard of Mutapa before you mentioned it here.. and naming it Zimbabwe, might, might make it more recognizable (mostly due to its meme-like currency, at least here).. but let's not take any more risk. We have enough obscure civ/leader (in non-CF/Reddit term): Georgia, Cree, Maurya. Let's the next 3 be civilization we all familiar with to boost sales
(like Inca, Ottoman and Mali ._. - hey one can still wish despite Mapuche/Zulu/Scotland is coming )