Hi Jeroen,
I hope you're doing well. There currently isn't a ULP that can give you a table view of all of the components in your design with their respective attributes that is editable.
However the BOM-EX download on our website has a ULP that can make it easy to assign the same attribute to multiple parts. You can also add attributes in the library.
If I've misunderstood what you are trying to do please correct me.
Best Regards,
Jorge Garcia