I really do not want to get involved in this, so just one note for now:
1,5% noise limit is probably a different thing in Corona than in fstorm. In Corona it is an overkill, as values between 3 and 5 should usually produce good results. You can see that the Corona rendering is very smooth, while in the fstorm example there is still some noise visible (e.g. at the top of the image).
Other than that, 2 hours is definitely too long to get good quality on a 7700k, so it was either rendered for too long, or there are some issues in the scene, which affect render time.
I think a bit more fair comparison would be like this:
-make a scene render to acceptable quality in fstorm in the lowest time you can
-then try to beat this score in Corona
(or vice versa)