I found a workaround for the loss of TFSC that works on Firefox.

1. Create a "userChrome.css" text file: https://www.howtogeek.com/334716/how-to-customize-firefoxs-user-interface-with-userchrome.css/

2. Add the code found here for "Global UI font": http://kb.mozillazine.org/Pane_and_menu_fonts
Change parameters as desired.

3. For bold font add this line before the end symbol: font-weight: bold ! important;
Change parameters as desired.

4. Save file and restart Firefox. There may be other parameters available but these were all I needed,