If you provide wood pieces with some curves or rocks with overhanging edges, the loaches will use those to hide in/under & explore as well. I find the more of them I have the more I see them, and I keep them in two of my tanks. One has Eco Complete, which was not nearly as fine grained as the bag led
me to think it was when I got it, mixed with some finer sand size stuff, but it has all gone to the bottom layer now.
The other tank has a much smaller grained gravel with rounder grains, but still not sand. I have both the striped kuhlis and Black kuhlis on both substrates and so long as they have plenty of places to hide underneath, not being able to dig in does not seem to bother them. They do dive for the cover, but they just squeeze under the decor and seem quite content with that. I have also not seen any sign of excessive wear on their barbels, which is one reason many want to use a softer substrate for them and for cories too, who also have barbels.
I keep cories with the loaches as well as Panda garras and a few dwarf loaches and some Otos. They all seem to find enough to eat, I've had no problems with them getting along with each other. But I give them lots of rocks and wood to hide under when they want to.
Fwiw, Black kuhli loaches, though they lack the wonderful colour and patterns of their striped cousins, are much more outgoing and active, even in the day.
I often see mine doing the ferris wheel, which is what I call a behaviour they indulge in, where up to four of them will chase each other in upright circles near the glass, over and over, for as much as ten or fifteen minutes at a time. Not sure why, but they seem to be enjoying themselves.
They get on well with the striped Kuhlis, but I keep a fair number of both species, since they do prefer the company of their own. I often find the striped ones lounging in the floating plant cover, draped over stems and leaves.. in broad daylight too. This happens most often when I have left new plants floating before I plant them, so the cover is quite thick. I really think numbers are why they are confident enough to do this.
Both tanks have an internal pump, a Koralia Nano, which provides extra current. In the one tank, the pump ensures a current for filter feeding shrimp, but the Cories and loaches certainly don't seem bothered by it in the least.. they seem to enjoy it.