I got this trouble when I was starting translation of AGS 2.3 game. It's use unknown for me *.wfn format for font.
If you have WFN Editor or TTF 2 WFN (for better), give link.
p.s. I heard, TTF 2 WFN converter was in pak of Corel Draw 2.x
The only font editor I know of for AGS is Radiant's Font Edit. I didn't even know .wfn was a normal format outside of AGS.
~Trent
It is not possible to convert TTF to WFN, since TTF is a vector-based font format whereas WFN is a bitmap-style font.
AGS versions prior to 2.4 did not support TTF, so in this case you can only use one of the supplied WFN fonts, or a custom one drawn with a tool like Radiant Font Edit.
Since the game author is still interested enough to ask you to translate it, maybe they can upgrade it to a more recent version of AGS to allow you to use a TTF font.