I have tried importing it via the CSS editor located in the edit theme area, however none of the fonts (icons) are rendering.
Although this is not directly connected to Vanilla and more of a general CSS question instead, somebody might be able to help you. But that would certainly be easier if you show us the code that you have added and what you expected it to do. Even more helpful would be a link to your page.
I have this import at the top of my vanilla CSS file: @import url('https://ventionblobs.s3.amazonaws.com/css/fontawesome-all.min.css');
I expect this to allow me to use a fontawesome class to display an icon. E.g. <i class="fas fa-arrow-left"></i>
Here is the page, icons are supposed to appear in the footer: https://vention.vanillacommunities.com/
In my humble opinion it all looks as if it should work, but it obviously does not...
By the way: this is the support forum for the open source version of Vanilla and you are a paying customer. You can also ask Vanilla's support for help