Hello!
I haven't really thought about translating the whole book in another language, mostly because this would be a really huge task, considering that chapters, code comments and even some images would need to be translated.
This project is continuously evolving too, which would make the effort even greater: the book has gone through many big and small transformations and I can't think of a system to track the translation effort on top of my head.
If you want to translate the book to Spanish, I'll be more than happy to be of assistance!
To be able to translate the book effectively you'll need to know Markdown, which is pretty easy, as well as the Git version control system and use either GitHub or GitLab (you can check the "source code" links in the "More information" box).
If you have any questions, feel free to ask!