use language('nl') to switch between languages, as DrawBot is typesetting environment...
font('/Users/frederik/Downloads/source-code-pro-2.030R-ro-1.050R-it/OTF/SourceCodePro-Regular.otf')
char = "б"
fontSize(200)
text(char, (10, 100))
language("sr")
text(char, (150, 100))