But there is no basis whatsoever to call this design
Ritchey-Chretien.
As Valery said, the RC has two hyperboloidal mirrors correcting for
spherical and coma. Any corrector that would significantly change
this
configuration couldn't be called an RC. And two fast hyperbolical
mirrors with the rest of the package would definitely require higher
price, even for only decent optical quality. Still puzzled...

I'll bet that they use spherical primary and overcorrect for spherical
with the front corrector to exactly the amount required as if it was a
"true" Ritchey-Chretien (making the combo behave as hyperboloid), then
use hyperboloidal secondary for full aplanatism. But as Valery said,
there is no escape from field curvature as primary and secondary
mirrors' paraxial radii differ too much. Free from coma, yes, but with
field curvature (milder than in SCT as secondary magnification is
lower).
That impressive spot diagram would look very different if it was
focused on a flat focal plane ...

Bratislav