Hello,
Josh Gay (w:user:Joshuagay) is currently working at CK12 on developing dozens of CC-BY math and science books for high-school and late primary students. Their current books are all English texts. They are also working with a small group to translate some of them into Spanish.
* CK12 would like to make these works available to Wikibooks (they already are in one sense, but in another they're only directly exportable as PDFs).
They use a cutsomized mediawiki for their internal platform, with Semantic MediaWiki, a second custom-made math parser-function for better math rendering, &c. So there are some minor hurdles to be overcome before the underlying wikitexts can be shared directly.
* Josh is looking for help with their translation process, particularly into Spanish, and would like to work with some Spanish Wikibooks editors and others to design a friendly toolset and process to make translation easier. (hopefully this process will be available to wikibooks in general, and will make translation easier all around)
Feel free to discuss here or get in touch with Josh directly (copied here) if you can help with import or translation.
Cheers, Sam.