There are over 100 species of Apistogramma, found all over South America. Even some as far south as Uruguay which may prefer harder water, and even winter cool downs.
That said, most types found in the hobby come from northern S America, and are from soft, acidic water habitats.
Some of these line bred types that have been in the hobby for 100 years may have built up tolerance and adapted to hard water, but if pH and other factors are too high, may produce single sex spawns.
Mixing your hard water with RO/DI, or rain water could help.
Also adding tannins could be a plus, especially because of their antibacterial quality.
I have soaked leaf litter to get tannins, peat moss, or hanging old tea bags in HOB filters to take advantage of them
for these type soft water fish when I lived in a similar hard water area.

I also put leaf litter in tanks, just like they might experience in nature.
