I'm glad it's working out for you at this moment, but your fish are still babies. The dynamics of a tank can change considerably as fish grow and mature.The 3 of them (two Africans and 1 South American) co-exist nicely.
Well that also is a valid issue with different types of Africans as well. I have two carnivores in a tank with herbivore mbunas. Not an easy mix to keep! The carnivores are from 1) lake Tanganyika 2) Malawai but a different part then the Mbunas. The Carnivore's I own have to be target fed and it's not easy keeping the Mbunas away from their food. I have had occasional Malawi bloat issues(when you feed too much animal protiens to a mbuna) so the next day I don't feed anyone and it goes away. But this becomes multiple issues with a mix of south american and africans. Water preference is very different between these continents as well as diet to some degree and tank size because the south americans generally grow much larger then aggression differences. So basically you need to have a huge tank and lots of time to bend these rulesAfrican's in general (my view) prefer hard alkaline water while the South American ,Central American cichlid's, prefer softer more acidic condition's.
Is difference in diet's as well.While the larger South American's,Central American's,need a fair bit of animal protein's to develop to adulthood,,the African's are more herbivorous, and easily become bloated,sickly,with too much animal protein's and not enough vegetable,algae,based food's.
No one tell's the poor African's that too much meaty food is not good for them, and they will happily eat all they can and as mentioned,,become bloated.
Don't think the African's can easily digest the meaty food's as easily as their larger cousin's.