font proprties (fontname, fontsize, bold…) in labels or textfields does not work in rpi jessie with 2017R2.1.
I can get font work in canvas with:
g.TextFont = "Roboto"
g.Bold = True
g.TextSize = 48
g.DrawString("Roboto Bold 48", 10, 80)
So problem is not with font, it’s just that labels etc. ignore font properties.
Btw. It’s only with rpi, same program with linux mint works fine.