Same approach: CGEventPost with Accessibility permission. The wrinkle was that my App Store reviewer wasn't comfortable with how I was using AX permission for auto-paste, even though the mechanism is the same as other apps already in the store. The clipboard-only version of WhisperPad needs no AX permission and that's what got through. Interesting that your sandboxed app with similar mechanics is approved.

Wondering the same, there is some weirdness around the clipboard and CGEvents though. Are you avoiding the clipboard entirely in your implementation?