If anyone is interested, the
Category Tags plugin now have the ability to export/import both notes and links to/from csv files. The plugin main function is to export/import user categories for items like authors, tags ... etc. Now, it adds notes and links in addition to user categories.
So the net effect is that you can export the data to csv file that can be opened with any spreadsheet program like excel or libreoffice calc, and edit the the data, then re-import it back into calibre.