You would need to modify the plugin to add a “Publisher URL” field — the fields are not currently filterable. If you’d like to do that:
– The fields are defined at plugins/genesis-author-pro/classes/class.Genesis_Author_Pro_Book_Meta.php
– The publisher is output at plugins/genesis-author-pro/functions/template.php in genesis_author_pro_get_book_details(), and would need to be adapted to include the link.
Note that changes to the plugin would be overwritten during plugin udpates, though.
One alternative is to use one of the three buttons to display a link to the publisher’s site instead. For example:

Thank you so much for your offer to contribute French translations. You can do so from this page: https://translate.wordpress.org/projects/wp-plugins/genesis-author-pro/stable/fr/default. (If you have a French translation file already, you can upload that with the “Import Translations” link in the bottom-left of that page.)
Thread Starter
celeb
(@celeb)
Thank you, Nick. I uploaded the French_CA translation file.