@potestus - as a result of doing those steps, the next time you do a metadata download with the Goodreads plugin then depending on the book you may get more Calibre tags coming through from Goodreads genres and subgenres. It is still completely dependent on the book and what genres it has been assigned by the Goodreads librarians, obviously dwanthny's mappings should give you a higher chance for more tags than before and I would guess with more granular tags for the genres.
To verify the config file is ready to take effect, from the metadata configuration dialog if you click on the Goodreads plugin and choose to configure you should see a very long list of Goodreads genres to Calibre tags.
If you don't get more Calibre tags - most likely it is because of that particular book (click on the Goodreads link in the book details pane to see the webpage and compare the genres listed for it with your mappings). You must also make sure that populating the tags field is set, and that you haven't overly restricted the maximum number of tags to be downloaded (all configured via the metadata configuration dialog).