The keyword guide has new guidelines on subgenres. There is a long list of possible keywords.
Some entries such as crime-documentary and music-documentary seem unnecessary given that genres like Crime, Music and Documentary can be combined in any search. These keywords seem to violate your existing rule against repeating genres: "For example, we have the genres Romance and Drama so you can submit these as genres to the title rather than submitting the keyword romantic-drama."
Some of the new entries duplicate existing keywords. For example, do we need police-procedural-crime when we have police-procedural, which can be combined with the Crime genre in a search?
Is classic-animation a subgenre? How would you define it?
Some entries just seem awkward, like docudrama-drama or winter-sports-sport, which may mean your contributors (like me) won't use them.