Just to be sure, are you trying to fix your fonts issue using Figma in the browser? The Figma font installer is only needed in-browser, and if so, you can find it here:
I just figured out the issue with the missing font not seen in Figma, even though I can see the same font in Font Book. It’s when I add in Library/Fonts is when it works again.
Seems like this folder stores specific fonts that Figma check in. Maybe…BUT it works! 🤩