Does Bookshop.org share customer info with affiliates?

Yes, but only bookstore affiliates - not other affiliates. 

If a Bookshop.org customer affiliates their purchase with a particular bookstore (from Bookshop.org's store finder page), that bookstore affiliate will receive information about the customer's purchase. This is because Bookshop.org considers such purchases to be made from the affiliated bookstore and gives those stores access to "their" customers' order information.

This customer order information is not made available to any other affiliate or partner of Bookshop.org and will otherwise only be shared in accordance with the Bookstore.org Privacy Policy.