If there is no signage, then this is not a living zone, regardless how the zoning plan designates this. If there is signage, then the speed limit is exactly 20 kmh for all roads within the signed zone limits (and all the other traffic law restrictions).

Can you link to the document(s) you are looking at? As far as I know, municipal territory/zoning plans do not indicate actual living zones as per the traffic law and only functional zoning.