So…. when you have a fleet of mixed subs/surface warships being attacked by only planes, you CANNOT take the subs as casualties?

IMO the allies do indeed have the upper hand.  US can easily ignore Japan and pour everything into Europe.  Japan trying to take west coast or even build enough stuff to scare the US is not going to accomplish anything besides wasting 2x as much money as the US spends to defend it.  In the games I’ve played Germany is pretty much sunk by the time Japan has enough to put a legitimate threat on Moscow.