Bottom line, most people (that play games) know english as a first, second or third langauge, so they can mostly understand (even if you don't understand everything in text, there's music and pictures to help). So if you like make a game in your own langauge, but also make it in english (and if you don't know enough english, then ask somebody to help out).
I mean, if you make a really good game and it doesn't have an english version, probably 90% of people at least on this forum (and these are the people that are interested in AGS games the most after all) won't play your game. It is not a question of national pride, no matter if you're Russian, French, German, Italian or from Spain, you gotta face a fact - you're language is not that important in the world that everybody knows it. Everything is served to this nations on a platter, everything from, books, movies and videogames is translated in your langauge and you get this false sense that the whole world uses your languge, THAT IS NOT TRUE.
English is rather simple to get the basics of, it doesn't have unusual letters and is native to AGS itself, so you can be sure it's compatible. Don't do it in english and you'll lose a lot of publicity and gamers. Simple as that, if you don't want to make an english translation, then don't make it in english.