I've never developed film at 22ºC. Just simple developer tests with totally overexposed tiny strip of film.
I usually develop film at 30ºC or sometimes, if ambient temperature is high enough, at 38ºC.
All RA4 prints I've done so far were from 30ºC and 32ºC developed-film.
Tetenal Kit manual states precise times for 30ºC, so I stick to it.
I sometimes developed at 32ºC, interpolating time, and the results seem nice too.
I didn't see any crossover, or at least I'm not aware of it.
I also scanned most of the images from these films, and colors come out well enough, with high fidelity, even if no digital adjustments are done.