Currently FreeSans Normal is translated to "odmiana zwykła". For easiest reading this should be "Normalny", starting with capital.
FreeSans Oblique is translated to "kursywa". It's ok, but starting with capital too would look nicer: "Kursywa"
Same thing with FreeSerif
FreeMono is ok!
So:
Normal = Normalny
Oblique = Kursywa
Bold = Pogrubiony
BoldOblique = Pogrubiona kursywa
Hope that helps.