My understanding is that you would get credit toward the certs as follows:

500 for GVA/FRA.
3660 for FRA/BOS.

Total of 4160 miles (i.e., you're not even halfway toward those certs.)

That's it -- nothing for C class, nothing for any kind of bonus whatsoever. Miles flown. Period (excepting the 500 minimum, of course. Which, by the way, does NOT apply to Shut-Hell flights, which is actual miles only with no minimum).