I use fontAwesome glyphs since 2016 all the time at work, basically they are webfont files now, in five different formats to cater for all browsers: eot, svg, woff, woff2 and ttf. My own website uses them for social networks icons and menu icons (this one on mobile devices only).
if you visit my site and see 3 social networks icons on top, then your browser can read these webfonts.
currently I use the version 5 of FontAwesome (https://github.com/FortAwesome/Font-Awesome/tree/master/webfonts)
And this works on all major (modern) browsers (edge, safari, chrome, firefox) and also Opera.
I thought that they should be working on SM 2.32 since its Fx 35.x based but no...
Bootstrap’s and FontAwesomes glyphs are the most used ones in the world.
like goodmaneuver said earlier, it’s possible that something is preventing the download of these webfonts by the browser to correctly exhibit them