Yes, what that message means is that the ISBN/book you were trying to Import to your Bookshelf isn't in the EYB Library at present, but it will be added to our Requested Books list. When that ISBN does get added to the EYB Library, it will automatically be added to your Bookshelf.
In fact, that's what's just happened! I checked the EYB Library/Books sorted by Date Added to Library, and the two books you recently tried to Import are at the top of the list, and have been added to your Bookshelf.