Brief description of the problem: I don't use all the fonts that figma has by default, so searching among the fonts becomes a torment, if you are looking for a font, going through all the options without having a specific idea or a specific font name, it takes too long.
 

Figma already has a suitable logic to solve this problem. You already have a dropdown menu where you can select font groups (All fonts, In this file , Google Font 8/24 Update (????) and etc.). 

Add functionality to create your own font groups where you can add the fonts you want and name the category. For example (UI Fonts, Sci FI fonts, Handmade etc.). 

This would make it very easy to interact with the font library.