TTDPatch is available in a variety of languages. To choose a language, please refer to Language Selection.
It is very easy to add more languages. I just need people who are willing to translate either the program texts or the documentation, or both. For translating the program output, download the program texts for all languages that TTDPatch has been translated to. Please change only the text that is in double quotes, the comments should remain the way they are, to make things easier for me.
I'm using Texinfo for the manual itself, which makes it possible to have a single file that can easily be converted into a pretty-print file (Postscript or PDF) as well as HTML for online documentation and a nicely formatted plain text file. If you want to translate the documentation, it would help if you know Texinfo, but it's pretty easy to figure out, so you shouldn't have a problem translating it.
If you have any questions about this or would like to help translate it, please contact Josef, see Contact Information.
You can get the current version of the manual in Texinfo format from the TTDPatch source code page.
For translating TTD itself, Csaba Varga has written the excellent TTD Translator.