>>> from PIL.ImageFont import truetype
>>> import os.path
>>> fname = 'C:\\temp\\Шрифты\\font.ttf'
>>> os.path.exists(fname)
True
>>> truetype(fname)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\jenyay\.virtualenvs\outwiker-lFR0QK22\lib\site-packages\PIL\ImageFont.py", line 261, in truetype
    return FreeTypeFont(font, size, index, encoding, layout_engine)
  File "C:\Users\jenyay\.virtualenvs\outwiker-lFR0QK22\lib\site-packages\PIL\ImageFont.py", line 144, in __init__
    self.font = core.getfont(font, size, index, encoding, layout_engine=layout_engine)
OSError: cannot open resource