In case there is some interest, I changed _mathtext_data.py to support nonslanted uppercase greek characters rather (\Omega & stuff, see .diff).
BTW, in _mathtext_data.py there is a line
font = FT2Font('/usr/local/share/matplotlib/cmr10.ttf')
I think this is a obsolete location, right? (at least I don't have it)
_mathtext_data.py.diff (1.73 KB)
Random number generation is the art of producing pure gibberish as quickly as possible.