We discovered that the new font versions now rely on the GPOS
table for kerning. However bare freetype (as used by CGUITTFont)
doesn't read this data. This caused kerning for these fonts to
stop working.
The new files were generated by opening the fonts in FontForge
and immediately exporting them again in TrueType format after
enabling Options -> OpenType -> Old style 'kern'.
No other changes made.