Thanks Daniel, I see how it is, and understand it is the way to make the font available in the font list of Hype UI. But perhaps, uploading the css and all font files generated by fontsquirrel is easier: no need to rewrite the path to the font files. Also most of front end designers will prefer to have a css rather than a < style > in the head.
How I see it: a field for each font filetype, the same way we have a field to upload different media formats (mp3/ogg/wav) in the resource folder. It is the difference of management of external resources I found strange for the fonts. When I click the + sign at the bottom of the resources, I expect to save a file in the lib, not to modify the head. My two cents.