The wording is ambiguous, like "missing road": does that mean that a real road is missing from the map, or that a road on the map not there in real life?
Most drivers are not thinking in terms of what Waze "doesn't allow". How would they even know, without having WME open, that the problem is a turn restriction vs. bad speed data, etc.? In this case, I think the wording should be, "Turn prohibited". "Prohibited" implies a real-life legal authority, as opposed to an internal map database setting.
That said, it is also possible that a Wazer might have wanted to report some other issue, and "turn not allowed" seemed like the closest category, even if it has nothing to do with turn restrictions; e.g., the roads at this junction meet at too sharp an angle on the map, or the intersection isn't quite at the right location.
The problem is, many of the "Map Problem" error categories are unclear, and the list is incomplete--not to mention, more than one category ought to go to Waze HQ rather than to map editors. Waze navigates you to the wrong address? The store is no longer at that address? We map editors can do nothing about those things, so why send them to us?
Waze needs to take some time to consider, from a driver's point of view, the entire gamut of problems that they might want to report, come up with a way for them to classify them as clearly and easily as possible (considering they are probably operating a motor vehicle at the time), and then make sure they go to the right people.