I was looking at the font and the part that doesn't have letters is very similiar to the windows 3.1 ega80 cp437 or the acorn bbc 128 font. (see examples here: http://robhagemans.github.io/monobit/) In addition, they seem to display correctly on the calculator. This means that escape sequences don't work right? I tested it and something like \n (ascii value of 0x0A) produces the altcode of 10 -> ◙ , which confirms my question.

So basically if I want to use gfx_PrintStringXY("\n"...) I need to manually detect the newline and use another function on the next line right?

Just use fontlibc for heaven's sake. You can even modify the characters in graphx >.>