Annabelle wrote:1) the first 7 books are for recent additions or ages with recent updates,
Gap (8th position)
I can only assume the empty tray is left there so that the "most recent" books stand out as separate from the "featured" books.
One of those wooden separators would have been much more ideal. If you look at the trays on the bottom shelf (when they're empty) there seems to be plenty of places separators could have fit in.
Sadly, the problem is that all of those trays actually have a leaning book which would get in the way...
Annabelle wrote:4) a special book to link to Crowthistle Ages <-- your 2nd Gap must be that book
That's odd that it looks like the Er'cana book from MOUL.
Well, so does the Elodea book but it has the title "Elodea" added.