The help page seems clear enough

Cell H21 says 80 is the speed in kph at which the sink rate is measured.
Cell F19 says .62 is the sink rate in mps

The glider weight is included in the wing loading column.

I don't have much interest in discussing failings in these calculations because I'm pretty happy to have the spreadsheet as it is.

OTOH, if you have energy to put more gliders into the data set, that would be interesting.