I'm currently trying to debug a font problem under 16.04 LTS. I have installed some TTF fonts in /usr/local/share/fonts, and some programs (such as gnome-specimen) correctly show all four font faces (normal, bold, italic, bold italic), but for some reason both the normal and bold font have a face name of "bold". This drives some programs (such as libreoffice) into trouble, since the cannot distinguish the fonts anymore and show only one of these two faces called 'bold'.
I've debugged this to the point that pango reports four font faces for this font, but two of them (although different) with the same name 'bold'.
Strangely, the face names pango assigns to fonts do not occur in the font files themselves, and sometimes font faces even get german names (e.g. 'Fett Kursiv' instead of 'bold italic'), although this string does not occur in Font files.
I guess it is a problem of fc-cache.
Where does pango/fc-cache take these faces names from and how to debug/fix that?
Which daemon generates the files in /var/cache/fontconfig, and how dump their contents in readable form?