While I was trying to fix the "Lang.? Missing!" error I was having, and I found out that the lang files were simply text files anybody could I edit, so I decided to translate that and the "mission" and "keys" files into my native (or at least one of my native) language: Scots! (Not Gaelic, the Germanic language)
Here are some screenshots, note that Scots is actually the closest living language to English, because it derived from English, so you're going to see many similarities to English and even be able to understand some of it, it's like, say Dutch or a Nordic language, but to a greater extent:
If anyone wants to check it out, the download link is here.
Anyway, I saw somebody make a Czech translation of the game, which was another language that wasn't officially supported, and I remember them being told that they should give the files a ".cze" extension, but the only way I was able to get my lang files working was if I used the ".usa" extension, (although I named them as ".sco" files in the download) but the files for me were originally ".eng" files, which was what caused the original problem for me. So is there somewhere where you get to select the language or something?
Is there something I'm missing or... ?