drumorgan wrote:The system checks itself to some extent. I added some roads and evidently forgot to "allow" a turn. The next day, I noticed an alert where someone made a turn that was not allowed.

I fixed it right there.
Where turn restrictions are incorrect, Waze itself will typically allow those turns if they were never set as 'hard' restrictions before when someone drives that direction. As far as I know, the directionality ( one way or two way ) should not be changed anymore, but there were reports of some roads where this occurred in the forums today. It was brought to support's attention and the original reporter said that it should not occur again after 18th Dec.
If hard restrictions are set, Waze will generate an automated 'Map Problem' that editors can assess and fix, like in your case. This is also the case where users drive over roads or intersections that are not connected, and Waze does not see how you logically got from point A to point B.
pamount wrote:With different users editing the maps online is there a governance process for checking the accuracy of the map edits? For example if somebody made some mistakes would the mistakes be picked up and corrected by somebody at Waze?
I'm not sure if you are an active editor or not. If you are, there is no reason why you cannot get stuck in and correct the wrongs in the area to bring it up to scratch. If the edits were recent, you might want to PM the recent editor and verify that they are done with the area and raise the concerns you have with him/her, or just let them know that you will be working in the area too to fix it up.
If you prefer not to edit yourself, I would suggest posting a request to update or tidy up the area in the
Country-specific Australian Forum requesting an Area Manager or CM to look into it and clean it up for you. I'm sure they would be happy to oblige such a request.