From the perspective of a translator, the first Fate/Complete Material Artbook was easy mode. It had the most artwork and the least amount of text out of all the Type-Moon artbooks. While it was still a decent challenge for a translator it is a cake walk compared to the later books. The first book was mostly just the CG from the game with some extra material. In many ways, it works perfectly as a test of the viability of the licensing of the series for the English market. Start off with the easiest book to adapt before diving into the more complicated morass of the later books. Character Materials has interviews and long boxes of text. There is still a lot of artwork but this book has meat. Since Type-Moon fandom is such a lore based fandom it makes the book much more valuable since this is where the real insights and revelations are held. The true Dark Souls starts here.
Back in 2012 I did a post about the five Type-Moon projects I would love to see translated. Since then some of my dreams came true and at the same time others of them are still unfulfilled. That said we finally have a fully translated 
Reverse Thieves 