I have not played against a 4 VP opening. How often is a true 4 VP opening achieved?
It is true that the rough description indicates a US relief of Australia is necessary, but the US can bring plenty of relief to Australia in three turns. It would be a small matter to get six US ground units, and six US fighters into Australia in three turns. That combined with the use of the Aussie forces should end the Japanese momentum threatening New South Wales.
After that, a set of bombers and fighters may be purchased to be sent to Wake along with a large US surface fleet including three or more CVs to the sea zone between Japan and Wake. Using some sub stalling of their own, the US could keep any large attack away from this part of the map for two turns while the US sends bombers from Wake and fighters from the CVs as escorts to SBR Japan.
This is strictly theoretical since I have not faced this opening strategy. It just seems to me the IJN does not have enough income to conduct a major assault and defend the homeland from SBRs.
Some folks may think that the carriers will be sunk by Kamakazies. I think that it could happen, but it is far from a sure thing. The IJN only gets a few of these and if that doesn’t work, they are done.