Hi Norbert -
Thanks for the help (and info!) After a little more investigating, I think you're right -- this isn't a texlive-fonts-extra problem. I had assumed it was because that's the only thing I know of in the TeX system that uses font awesome, and the glyphs broke after I added texlive-full on a fresh Stretch system that already had the i3 and fonts-font-awesome packages installed (I can remove texlive-full and things work again). Running
$ sudo dpkg --remove --force-depends texlive-fonts-extra
to specifically remove the fonts-extra problem doesn't fix things which seems to indicate the problem is with another part of texlive-full. Do you know of anything else I can check to iron out what might be causing the problem? Running
$ fc-list | grep -i awesome
gives me the same output as you.
Thanks!
~Connor