The problem: Right now after just installing fonts, they do
not become available. This can lead to some applications
appearing "broken", etc. Other operating systems solve this
by having a post-install hook which roughly does just this.
A possible solution:
Our fictional, not yet existing, font-build-system should
run "fc-cache --force --really-force", or we should have
a service which does the same for the fonts installed in
the user profile.
At this point a font-build-system would be good anyway,
as the number of fonts keeps growing, and most fonts are
using similar patterns to be installed.