The Ruby & Sapphire were released in Spanish as well … and about release day, the information has not been well-preserved, but we can have an idea of when approximately they were released … I’ve written an article of the first wave of Ruby & Sapphire (Spanish)
Yes. It’s unknown why Devir decided to distribute Spanish cards in that way. The information about the release of these Half Decks in Spanish (I mean, something in Devir’s website mentioning the existence of these Livros Ilustrados) is actually Lost Media.
The Livros Ilustrados from Unseen Forces in Spanish were found relatively recently. Almost nobody knew the existence of these product in Spanish and it wasn’t documented on Internet. In fact, as the day I’m writing this, the articles of these products on Bulbapedia affirm wrongly that they’re Portuguese exclusive (when they’re not)
Thanks for mentioning my article … 
In that article I only wrote about Ho-Oh Livro Ilustrado in Spanish (and mentioned Lugia one briefly). Reason why title says (Part I).
Btw, Lugia Livro Ilustrado in Spanish (Sealed and with the warning from Devir telling that cards are in Portuguese) has not been found to this day, but this deck definitely exists in Spanish.
I’ve thought in developing a remake of the Unseen Forces Spanish Livros Ilustrados article. I don’t know when I’ll publish it tbh …
