Earlier quoted context omitted.
Don't use font icons, I use svg icons with and works great. Much easier to customize when you need to in my opinion.
Font Awesome uses font icons, and they seem to have accessibility figured out? https://fontawesome.com/docs/web/dig-deeper/accessibility
https://fontawesome.com/docs/web/dig-deeper/webfont-vs-svg
One of the key notes in the bottom table on that page is "Auto-Accessibility" and the JS libraries with SVG icons provide better accessibility out of the box. Most of the document you linked is stuff you need to do manually by default when working with web fonts.