Lower their temperature, for sure! Try lowering it to 75F and then doing cold water changes. The rest of the parameters look pretty good. If no powerhead or wavemaker, that can also be very useful to have.I have kept paleatus a few times on and off over the years. They were in my early tanks. Then not again for some time. Now I have the long finned ones. What I discovered with my first batch of paleatus is that how they look depends a lot on the light source. Look at the pics on Planetcatfish for them, Ignoring the albinos they still run a gamut. I think a lot of that is lighting and the rest may be geographic difference?
I do not breed corys ofr the most part. So I have the paleatus, a few sterbai and albino aeneus. The one group I got inorder to spawn them have not been cooperative. These are the black Schultzei. A friend sent me six of her offspring. Then I bought six more for a measly $20 as part of my fish club's grow out contest. Unfortunately. I could not turn in my 3 biggest for the judging as I was a vendor at the Keystone Clash. My club scheduled the turn in date after I had registered for the Clash. At the recent clubs Xmas dinner meeting I grabbed another 3 small black Schultzei so I now have a total of 15. However, I doubt if more than te original 6 ae big/old enough to spawn.
If you have any advice on spawning the the Schultzei, I would appreciate it. They are kept at 78F, in basically neutral pH and with TDS in the 120 ppm range. (4 - 8 dH, 70 - 140 ppm : soft) My water is from out well and over the years it has been about this hardness but at 7,4 ppm. Then it dropped down to more like 80 PPM TDS and dead neutral. Over the past year the TDS has risen from 83 to its current 120 ppm.
If they're really stubborn, could always attempt the dry season/wet season method
I had the schultzei back awhile ago, they spawned relentlessly

Kept mine at 76F, pH 7, GH 5° KH 3° unsure on TDS, last I checked it was like 90 but that was eons ago when I had a TDS pen and used it for fun.
They spawned heavily towards stormy weather for sure, and often following water changes. I lost my original group awhile back, however. But babies I sold to someone else, they bred them, though I think they crossed them with true aeneus. A friend of mine then bought those babies from that person, which then bred in turn, so I now have a group of them now which show traits of both aeneus and schultzei. They're not being further bred by me, as I question species purity here, but it's nice to have some "great grandbabies" from my originals just as pets. That said, they're already barely a year old and chasing one another around in spawning attempts

But 78F is very hot for spawning any cories, most need colder end of their ranges and cold water changes, since most breed during the colder rainy seasons. So go 75F and ramp up the flow.