Rheophytes will be difficult there aren't that many around in cultivation and rather is an odd term, Rheophytes are plants that are (bog) plants that prefer or can survive fast-moving water. This could be anything that grows emersed and lithophytic or epiphytic in and around fast-flowing water.
Take for example Anubias is such a plant, it's an Epiphyte that also grows as a lithophyte in nature I bet it can be found growing on top of rocks in flowing rivers at that point this would make it a rheophyte. In the same condition, Bolbitis sp. and or Bucephallandra sp. probably can be found like this and likely many other plant sp. as well. In our regions in Europe, we have the Adiantum capullis veneris (Maidenhair fern sp.) that can be found in such conditions growing to the cliffs alongside waterfalls and it survives the full blast in the rainy seasons with ease and this makes it a rheophyte. That is actually what the term Rheophyte refers to...
The term rheophyte doesn't concern growing to a hardscape above an aquarium and could be any plant that can grow as or prefers to grow as an epiphyte.
And that's quite a lot to choose from if it will be a success is a matter of trial and error and several conditions other than air humidity that not always can be predicted. Temperature, light, fertilization, water hardness and air humidity in combination will play a role in success or not. Most plants that grow epiphytic are slow-growing plants that need time to transition to changes and I guess that is our greatest bottleneck for having long-term success in a rather fast-changing and rather unnatural indoor artificial environment.
I have seen Anubias sp., Bolbitis sp. and other types of Bog (aquarium) plants growing epiphytic and emerging on top of a hardscape above an aquarium and doing well. This proves it can be done but these are all very long-term projects with long-term transition and probably a tad of unintentional luck. For some it works for others it doesn't and there are no rules written in stone.
I would say hop into the Wabi Kusa hobby and use these techniques to learn to slowly transition plants to grow emersed in lower air humidity conditions. Learn and see what plants do best in the conditions you and your house can provide and work from there to pick a plant that does good.
Or you could go for houseplants that can grow epiphytic, but then make sure the roots are not in the water. Adiantum maiden hair fern and or Peperomia sp. might do good.
This is a Peperomia sp. placed in a bed of terrestrial mos from the garden and it did very well for over 6 months... But then all of a sudden it stopt loving that spot and died... Beats mee why... But those 6 months i did enjoy it a lot.
This once was a High Tech aquarium with enough CO² added.
When i ran out of CO² i thought to grow it on like this low tech... And it didn't, the sudden change was te much and all went down the hill from there.
It might be possible to grow this low tech but not with such sudden changes the plants don't get time to addapt to...