Your pH, may be the limiting factor. Although locally raised S American cichlids like Apistos might survive in that water, they wouldn't look their best.
Shell dwellers would do very well, and you could still use hard water plants, like Vallisneria, Anubius and Java fern with them.
You could also use some of the smaller rainbow species as dither fish in that water (dwarf blue, or Irianjaya specie), surface dwelling live bearers which prefer hard water would also work well.
Most tetras would find your water osmotically unsuitable, as would some of the soft water barbs.