If the officials missed the punch, I firmly believe it is up to the player's coaches to ensure proper consequences are given. If that player's coaches also didn't see it at the time, I would certainly go through your coach and club to escalate the incident to the appropriate administrators. Attach the video.
If my kid ever did that, he would have some serious consequences from mom and dad!
Rule 620 | Head Contact
(Note) Head Contact is the action of a player contacting an opponent in the head, face or neck with any part of the player's body, equipment or stick.
(a) A minor plus a misconduct or major plus a game misconduct penalty shall be assessed for head contact to an opponent.
(b) A major plus a game misconduct penalty shall be assessed to any player who injures an opponent as a result of head contact or who intentionally or recklessly contacts an opponent in the head, face or neck.
(c) A match penalty for attempt to injure or deliberate injury to an opponent may also be assessed for head contact.
In any incident where intent to injure is determined, it takes precedence over the defined penalty (ie fighting). If the refs are claiming they didn't see it - then it's tough to assess intent to injure.