I believe BitmapFont only GPLs the C++ program that parses the HZK*/ASC* data. The glyph data included in that project is collected from microcontrollers and DOS-era softwares. It’s known that companies at that era often use these data directly. However, since there is no clear copyright owner of these data, I think if you have strict requirements, you have to avoid projects using HZK*/ASC*.