The Cory info in the hobby is full of relics. I had a book when I was a kid that asserted there were paleatus, aeneus, melanistius and julii, and no other Corys. We've learned a bit since then.
What we haven't done is updated. paleatus was said to be the cool water one, and while that's true (tropical cool) so are most of them. We just keep repeating the same old story, over and over, and not taking in the new info on basic aquarium sites. They all just copy from each other and rarely research.
It's like "false julii". The real julii is rare and expensive, but because someone made a mistake identifying imported fish sometime in the 1940s, we still talk about the fish with the wrong name and info rather than just naming it as what it is.
My daughter breeds pandas at 21c. I picked up three "Corydoras" species this week, and I expect that when they reach breeding age, they'll work at 22c/72f.
"Corydoras" in in quotations because they've been reclassified. I actually got a Brochis and two Hoplisomas, but that will take time for all of us to absorb. We'll probably still be calling them Corydoras in 2134, if they aren't extinct.