Again, the program is not program in general sense. The real “program” part here is ttf format and protocol around there, but protection goes over ttf data as a whole. It may be able to argue if such new font display system is developed and used, no gamedev/publishing industries want to reinvent the wheel and built the ecosystem from scratch.

Also, even with such system copied fonts are likely sued because of Japanese law concept of “依拠性”, a concept related to similarly that accused product intended to copy/based on protected entity as long as end result is the same.