Disclaimer: I'm not a lawyer, but this is my understanding.

For the addon code specifically, as long as you're adhering to the MIT license as defined at https://github.com/Cherry/3D2D-Textscreens, you should be fine.

However, that's not the case with custom fonts, and you'll need to be very careful about the fonts you use. Most font licenses when it comes to distribution are exceedingly expensive to acquire. You will need to consult the licenses of each font before distributing them.