I used this plugin and went through my 7300 books to update my tags. I started with around 953 tags and now that I finished I am sitting at 208 tags.
I attached my goodreads.json file with the mappings in place. I wish I had a more extensive mapping when I was doing my update to begin with. For the most part I limited tags to 4 per book, sometimes I would trim back to 1 or 2 and for Non-fiction books I would often allow up to 8.
The only thing I don't have mapped is Contemporary, Modern, Adult Fiction and Adult. If a book pops up as erotica then the adult tag is also added to that book.
All of the mappings in the file work. The good news with this json file is you don't have to hunt around to see what is there and how to make it work and you can easily remove tag mappings, but since it is easy to limit tags to a particular number, leaving everything in place works great without gaining too many tags.
If you choose to use this file you must do the following.
1. Exit calibre
2. Unzip this file, you now have a goodreads.json file
3. Find the plugins directory under your calibre configuration directory.
4. Rename your existing goodreads.json file to goodreads.json.org in case you feel the need to go back to it.
5. Place the new goodreads.json file in the plugins directory.
6. Start calibre
Now you can go to Preferences - Metadata download - select goodreads - click Configure selected source to see what is currently mapped for goodreads metadata downloadable tags.
I am now running a modified version of the json file created by Huisie. This json file can be found here
. It starts with about 800 goodreads tags mapped. The Goodreads json file attached to this post has about 250 Goodreads tags mapped. Either is a good starting point.