With last betas (minimals) I can't use CFF flavoured OpenType fonts with
more than 1000 em units, the backed reports the error:
!LuaTeX error (file /pth/to/file.otf): Invalid font type
It appears this error is reported when luatex encounters a non TTF
flavoured font when it expects one (a more explicit error message or at
least reporting the invalid type would be more helpful, I think).
Checking ConTeXt, I see in font-otf.lua:
if units > 1000 then
fileformat = "truetype"
Which IMO don't make sense at all since CFF fonts can very well have >
1000 em units. I think this was to work around the bug reported earlier
about TTF fonts with .otf file extension, but this is likely to break
more other fonts. Renaming the other font is easier, meanwhile neither
file extension nor em units is a reliable way to detect spline type
(which I think is already known, since Taco has a tracker item for