Hey there and welcome to the Community @Jacques_HANEN 
I see that it would be great to have an option to upload fonts to the widgets. Could you please specify which widgets you primarily need this feature for?
As for now, you can check our CSS Codes category and find the needed code to change the font. If you haven’t found the code for your widget, just drop us a line and we’ll gladly help 
Also, you can import fonts to the widget via Import URL option. This feature is not available in all of our apps, but it will work perfectly for the widgets you are using (Contact Form, Search, Reviews, Logo Showcase).