The problem is most definitely NOT lipstick. Lipstick doesn't load any fonts. In Wayland programs are supposed to load fonts. Same as in modern X11, with Qt/Gtk+/fontconfig.

I suspect this is a problem with mapplauncherd, it is probably scanning for fonts before the fork() and not doing it afterwards. So every application gets the font set applauncherd got.

Maybe you can use something like
http://qt-project.org/doc/qt-5.0/qtg...pplicationFont
in order to manually add the font in your program.