In my exploration for more info on FFVI and the Settei Shiryou Hen books (they are pretty much the Ultimania books of the pre-VIII FFs), I stumbled upon a website that has translated one of the FFIV books.

Thought it would be interesting to share as it doesn't seem to have the same level of controversy as the FFVI one does. To give a quick rundown of what the site talks about...

It gives personal stats for the major cast minus FuSoYa and the villains. As well as a few minor details about the characters past that is not made known in the game. Nothing terribly world shattering but it does add a little context to a few things in the game.

It mostly deals with explaining a bit of the Blue Planets history as well some good detail about the countries of the world. Interesting to note is that according to the book, the history of human civilization on the planet is relatively short which may be a hint of the Lunarians influence on the Blue Planet.

Regretfully, due to the lack of sources to match this up against, its difficult to ascertain the legitimacy of this translation but as stated earlier, it doesn't reek of "fanfiction" as badly as some of the VI translations do since most of the new info does not contradict the actual game.