My #tagsGM is MY way of handling the issue you are trying to approach with very intelligent plugboards/created column solutions. Here's what I have done:
As I said, I have a #tagsGM column that is a list column with maybe 30 possibilities in it. One of which is Uncat (for Uncategorized). When books get added, they get tagged as Uncat. I have created saved searches that look for #tagsGM = Uncat and for tags to be equal to a set of possibilities that covers MOST of the variations I might be interested in for that particular saved search.
i.e. #tagsgm:"=Uncat" and (tags:"=Mystery" or tags:"=Mysteries and Detectives" or tags:"=Crime Fiction" or tags:"=Crime" or tags:"=Mystery Fiction")
I classify all of them as Mysteries in #tagsgm. Soooo, what I do is open the tag browser. The saved searches are at the bottom and I give them names like __400NewMysteries (note that's a double underscore for sorting purposes). I click the search, wait for a second or two, and then I get all the uncategorized books that I 'THINK' are mysteries. I do a quick look to see if somehow they should be categorized elsewhere (such as Non-Fiction, although I use my own ranking system to make Non-Fiction searches come before Mysteries in the searching sequence), then I Select all (ctrl-A in Windows) and press e to bulk edit. I then add Mysteries to the #tagsgm and check the box to remove all other contents from that field. Press OK and all the searched for books disappear as they are no longer Uncat books.
This sounds REALLY, REALLY complicated but it's not. I can zoom through re-classifying in about five minutes. I manually look at all #tagsgm:"=Uncat" afterwards and do a guesstimation on what the #tagsgm should be from the book description and any tags extant. I make a note of whatever in the tags that aren't in my system that I think should be in it. And Bob's you uncle.
By the way, when I was setting up these searches, I had the whole list in a notepad file. I then ran through my already categorized books and looked at the universal tag field I had gotten filled during metadata updates. By copying and pasting a section of the search, I could then easily type in the variation that I was looking for. I then copied the newly updated line into the Search editor and that way, I keep pace with the 'ingenuity' of the tag creators out there. I've had to update Mysteries and Thrillers several times, trying to create JUST the right smarts to make sure I get the division between the two correct. Your willingness to go crazy with the search parameters (including nots and all that) is up to you. I suspect you might want to search for things you think might be a little more erotically-rated BEFORE doing the search for Romance. And how you decide the order will put Romance before OR after Thriller. Again, up to you.
It would be nice to get super bright AI from the calibre column creator and plugboards, but sometimes a little manual elbow grease works out better.
But I could be wrong.
