Many thoughts, but I think Mistake Delay is ok for sure, at least to optionally Show Info.
Kana should be strict, yet Okurigana matcher can be optional, to prevent fat-fingered wrong.
I am in the camp that meanings in English don’t matter much, but it also depends on stages of learning. It can be hard to adapt to learner differences, from clumsy to outright misdoing; and one can be on both sides of the spectrum at the same time. The current implementation of string distance, and hidden warning lists and blocklists, are quite messy in my eyes.
So, I think it should be an option, although might not be the default one; just like native re-ordering, which gets implemented at last…