That sounds a bit weird to me, because it's like you're trying to change her origin to benefit yourself, even though her creators Gerry Conway and Bob Oksner wanted her to come from a fictional African country for a reason. Maybe there's a specific reason why they didn't have her come from Ghana.
Also, the reason why Zambesi may not be "very interesting" is that almost very little has been done to expand Vixen and Zambesi in the comic books for over 40 years, but that is DC's fault. If Vixen had been given the same amount of lore and stories and attention that Black Panther has been given thus far, maybe Zambesi would be "very interesting" because DC writers would have fleshed the country out more. It just feels as though Zambesi not being "very interesting" is being used against her and therefore, "let's make her come from a real-world setting."
Also, as uninteresting as Zambesi may seem, if Vixen came from Ghana, there would be very limited things that could be done with Ghana in comic books since it is a real-world African country. At least with a fictional country like Zambesi, you can build it up and make it a country of magic and mysticism or something. Something like that can't be done with real-world Ghana.
But those are just my opinions. Maybe a whole lot of other people agree with you.