"Gruntaleous has found a magic site in Gipsnicht"

mercury pond is listed as "water 1", which I think means you need a water1 or higher skilled mage to find that site.
Correct

Are those just possible errors in the spreadsheet?
Of course it is possible. You'll always find some mistakes in spreadsheet with 450 lines. I've found several mistakes myself. And IW sometimes changes things without warning...
I'll check any discrepancy you see.
Cheers