On slightly another tangent, the difference between Australia (BOM) and the United States (NWS) is that all tornadoes are investigated and rated in the US.
The description from eyewitness of the Bulahdelah tornado refer to rapidly turbulent scud action and low bases. Giant hail was reported that would indicate supercells on this day with smashed windows around Newcastle if I recall and the Mid North Coast.
Regards,
Jimmy Deguara