They should be fine, but they would appreciate hard structures to hide in/around. I would give them caves - they would like it more!
If you don't want rock caves, you could try to find good driftwood pieces to make caves out of! that's a few angles of a piece that really works for me as a corner cavern, there's lots of thinner tunnels through the bottom which the dojo loach really likes, the kuhlis would appreciate thin spaces like that too! Good luck searching
I hope here is a picture of my 29 gallon tank with 3 honey gourami. They are comfortable in the tank, they spend a lot of time in the jungle Val plants on the right. But they also like going in the hollow log on the left when they are startled.
I have kuhlies in a larger tank, they stay under a large piece of driftwood or under another hollow log in there.
New Fish in Town
It is important to give them some hiding places, so they feel safe. Being out in the open with no place to hide stresses them out.
Cardinals and gouramis don't need caves. Kuhlis like hidingplaces though-. And gouramis is an equivalent of floatingplants