FWIW, I have floated in the private TalkBoard forum the idea to mandate a non-sticky thread for discussion of moderation policy and practices in the forum excluding any discussion of specific past actions but allowing discussion of hypothetical future actions. The second part of this idea is that each forum's moderators would be allowed (as apparently they already are) to allow discussion of specific past actions to whatever extent and under whatever ground rules the forum's moderators see fit, subject to constraints, if any, set by the Community Director.
This version is both innocuous and flexible, IMHO. It could promote valuable feedback for some forums.
^^ Although I'm guessing your excellent proposal will go over like a lead balloon. All but a few of the moderators I've met & interacted with are wonderful, fair, approachable people, but there are others who seem very much afraid of transparency.