>What else do I have to consider to display the xxx.ttf files correctly?
You have not told us if you are using EVE2 or EVE3.
If you are using EVE2 things are a lot more complicated.
If you are using EVE3 then just convert the font to extended format,
put the .glyph and the .xfont file in the external FLASH,
copy the .xfont file to G-RAM on start of your programm,
use cmd_setfont2() in your display list to assign a bitmap handle to your custom font
and last but not least make sure you are using UTF-8 encoding for your source-file in
order to have your cmd_text() commands behave like you expect them to.
Something to be considered is the size of the resulting .glyph file.
If you are using a font like NotoSans from Google it contains a lot of glyphs and it might be a good idea
to convert the font first in order to remove several languages that you do not want to support.