I don't know if it was already mentioned by someone else.
But this current Rules/Guidelines doesn't talk about ninja spinners, or not enough explicit about it.
This rule "Spinners must be long enough for Auto to achieve 1000 bonus score. Shorter spinners are unreasonably difficult to complete."
And guildeline "Spinners should be used when they fit the music. They usually fit during held notes, changes in intensity, or transitions between sections. This is to ensure score differences among perfect plays on the leaderboard." are not enough explicit about what is a "ninja spinner", and if it's rankable or not.
By ninja spinners i mean a very short spinner (assume auto can still achieve at least 1000) but in a place where it is not predictable, and for sure, it is suprising for the player and he might combobreak.
The term "ninja spinner" should be added.
Edit, and did you talk about giving enough time after spinners, in easier diffs ?