As stated in MCPE-29941, the curses of Binding and Vanishing were never implemented into the Bedrock edition of the game. However, during my three hour trip to a Woodland Mansion, I ran across many villages. There was one in particular that had a librarian in it. He offered me the Curse of Vanishing book for 9 emeralds. At the time, I was tired and thought that I might just have missed the patch notes. But today, I was curious. The wiki said that the curses were never implemented, and the patch notes had no mention of them. So I opened up a new creative world. The curses could not be found in the creative inventory, and could not be given to items using commands. So I wrote an addon that made all villagers spawn as librarians and offer 6 enchanted books as their tier one trades. Sure enough, I was offered both curses from the first two I spawned in. I got the books. And applied them to helmets. And they did nothing. For the vanishing, I tried killing myself in ever conceivable way, but the helmet always dropped. For the binding, I just put myself in survival mode and was able to take the helmet off instantly. I am fairly confident that these books were accidentally left in the game after the beta update. This is not a huge issue, but it still needs to be fixed, as the librarians selling these books effectively have one less trade to use.

To reproduce:
Summon many librarians and eventually you will find one that offers one of the cursed books.