I am completely in the dark as to how IDesignR works and operates. If fonts can be imported into the program you can go to FontBros.com and purchase the font, and many more. I use their fonts for vinyl graphics as well as embroidery.
You are correct, for their free fonts. For any fonts that you purchase the license for, you can.From what I was reading you can't use Fontbros.com fonts in commercial products.