Native letters

[Kilitar]

I have similar troubles - with some Czech letters - ě š č ř ž ý á í etc.. they are corrupted/broken.
We are using standard english version (not translated XML/LUA) of FG, but we are trying to roleplaying in our own native language.
And we cannot use those letters neither in chat window, neither to create own libraries/adventures/items/NPCs

[Moon Wizard]

Some of the letters will work, but others will not. The fonts for most FG rulesets were built from the ISO-8859-1 encoding scheme.
https://en.wikipedia.org/wiki/ISO/IEC_8859-1
According to the Wikipedia page, there are a number of Czech characters that are not supported by this ISO standard.

FG currently only supports single-byte strings (not Unicode). We are not currently set up to support full internationalization of FG.

You could try writing an extension which replaces the fonts in the ruleset with fonts built using a different encoding, but not sure if the key codes received by FG from OS will match up. Someone would have to build extension and font, and test on a native OS system to be sure.

Regards,
JPG