Hey Fudgel, I have looked into your CSV. It is working as I originally intended: it only displays books that are on your "to-read" bookshelves, as the idea is that you want to find a book that is not on your read list. You only have one book that is not on your read list.
Would you want/expect any other functionality? I assume you then mainly use GoodReads to keep track what you have read and not what you would like to read in the future?
If you have time, maybe you can share your csv via e.g. wetransfer?
Thanks for taking time to look