I did som test with the title you gave:
I can reproduce any error: the only thing is the dialog that give you some options to choose, if the title did not match exactly.
The dialog is also shown when used in the bulk_metadata download.
before:
dialog
after:
Which version of bol_nl do you use?
What is the error you get with this title . The logs you gave are of calibre itself. The logs from the plugin are maybe more specific: In the dialog of the metadata search: "show log" or in dutch
"log weergeven"