I'm using that plugin and it is working fine. However, I have 2 bug reports:
You extract the editoral description as "Beschreibing Redaktion". There is a typo, it should be "Beschreib_u_ng".
For publishers with a very long name, bol.de shortens the name of the publisher. The plugin does not recognize this, leading to useless entries in the publisher column. An example can be seen when opening
http://www.bol.de/shop/home/suche/?sq=3641062659. Thats a book by Random house. On BOL that publisher is called "Ebooks der Verlagsgruppe Random House GmbH", which gets shortened to just "Ebooks der Verlagsgruppe...". However, the link behind the name contains the full name of the publisher. So maybe you could recognize this situation (publisher ending with an ellipsis) and grab the remaining part from the link then. The capitalization would still be wrong, but at least the full name would be there.
Regardless of those issues, thanks for providing the plugin,
Michael