Originally Posted by filmo
How are you deleting this book?
When you delete book from your Kobo book is still in trash folder until you empty trash. Book is still in Kobo readers data base until Kobo updates it's data base.
That depends on the type of book and the firmware version. If it is a kepub, then what you say is correct. The main record for the book is marked as deleted until the next sync. The rest of the records for the book are removed.
For other types, all details are removed. Except with firmware 2.0.0. With that, all books were treated the same as kepubs. But, it is the only firmware version that this happened with.
But, as far as I can tell, no version of Kobo firmware sends information about sideloaded books to the Kobo server. If it is, then it is definitely not sending the info back to the device at any time.