Thanks anyway I guess it's important to note that I'm from Colombia, so I guess it would be nice to have someone from Spain. You know, to have like an "standard" spanish translation (latin america spanish + spain spanish). So again, if you want to help in this project, just send me a PM.
After thinking about this, I decided to contribute with the English to Spanish translation. I just bought Xenonauts in Steam the last month and I remembered that in X-COM UFO the only language available was English. Now, I have the chance to contribute to make a translation for Xenonauts and that's pretty cool. In this thread I will post the updates of this project. Feel free to contribute in this!