Judgment by peers, not by management
An effective way of organising the interpretation of the (intent of) human behaviour is to create a “Just Culture Committee (or any other suitable name), with an as much as possible independent chair, with peers particiating in it. The peers must reasonably expect to see their own experience and professional judgement reflected in the end conclusion of the committee. This is essential for the justness of the conclusion.
The committee can make use of the navigator to assist in the interpretation of behaviour if necessary.
Make sure that the personnel involved has a high stake in defining where the line should be drawn. The professionals themselves know best.