Boy that manikus sure does talk a lot...
Uatu, you are correct about the game font. If there is a font that you simply cannot have your game without, you might try finding a freeware version (there are thousands of them out there) and include it with your download.
As for what happens when the expected font is not found, Dinonykos actually provided the answer.
Most fonts have meta-data that tells what font family they are part of (think CSS), so DC will pull a font from the same family. Some of us have thousands of installed fonts on our system, so we should be good.
As for that font...it is specifically the FRUA font. And it can be downloaded from:
http://one.xthost.info/elminster/FRUA_font.zip