That sand helps to buffer alkalinity a bit from what I understand (I use generic aragonite) it does not really elevate pH, just help to hold it steady.
Depending on what you mean by South/Central, most Central Americans, and the South Americans west of the Andes live in water similar to African cichlids, it's only those Amazonian types that come from softer waters.
I keep many Uruguayans, ornatum, festae (both from west of the Andes), even Guianacara and Acarichthys in hard almost African water conditions, as my water source is Lake Michigan, other than temp, has water chemistry similar to the African rift lakes.