I often use Kagi Translate for Japanese as a way to proofread, fix my grammatical errors, and more quickly notice if I accidentally selected the wrong characters for a word. I would love it if the proofreading feature not only checked my grammar but could also make rewording suggestions depending on how formal I want my text to be.
Since Kagi Translate does allow you to choose formal/casual for the output translations when you translate from English into Japanese, I'm hoping this would be an easy add!
For people with intermediate to relative fluency in Japanese, getting feedback on whether we've successfully nailed not just the grammar but the tone would be really helpful. I could see this being a really good tool for self-study or people who are out of school and trying to improve/brush up their skills without access to a teacher.
I'm not aware of any tool that does this, which is why I'm hoping Kagi can implement it!
