Yeah, it's a difficult line to draw. Enough catagorization to make browsing easy, but not too much to cause confusion. At the very least, there should be 3 catagories: African, New World, and Misc.the main reason we dont do that, is from what i believe is we dont get enough of those questions to even bother expanding it any more as it is rare for people to ask that, the same as me wanting the SW forums expanded before i realized not enough traffic
I would argue angelfish are more popular either than discus or apistos. Also apistos and discus fish could fit under SA as well, this may lead to confusion.
Another point is that many posters may not know if their cichlids are CA or SA, this also may lead to confusion.
Best of luck !