Range is to short for lack of movement, increasing the time you're vulnurable afterwards would be a good idea, making the easiest nudge to land the one that you can get a hit afterwards AND the one where you knockdown someone who is trying to kick you with prolly wasn't a great idea either.
Imo the alterations that should be made are:
Nudge while blocking: Knockdown kicking people, no stun whatsoever, if someone it is being done on is attacking cancel the attack, slow the nudger down to walking speed for like a second after nudging to prevent the nudger glitching into the nudged and getting easy hits that way, and make the nudge push people back about twice as much as it currently does.
Nudge while not doing anything: More or less keep it how it is.
Nudge while attacking: Tiny stun, completely worthless for getting an extra hit in yourself, can knockdown people who are nudging, can no longer knockdown people who are kicking.