If the US buys some ships to force japan to also Build ships the advantage is still on Japans side. japan needs ONLY to match the US builds at most. As usually japan has more BBs (usually) to soak up losses, It “only” has to maintain a fleet in "striking distance to the US setup areas. Of xcourse it needs fighter cover, but that is easily achieved as Japan has a definite carrier advantage (same as bbs) in the early stages.
I too often saw the US building up for a strike on Europe/Africa and then they had to go a few rounds against constant naval landings from Japanese troops. In the meantime Italy (must also build some ships IMHO) sailed out and damaged the US attack fleet while Germany spent a turn or two to strike at the UK ships.
IMHO if the Euro Axis strikes a balance betweed agressive defense and heavy blows on dangerous Allies - build up points (Germany has the inner line - often enough units used for an attack on one front are available for defense action on the other front next turn), they are in a 2-1 position for a win.
regarding an 8 inf attack on turn 2 on africa - yeah thats a really bad blow to the axis, thats why I NEVER saw a game in AA50 where Germany did not commit the bulk of its airforce/navy to take out UK ships in the biggest number possible. Sometimes the Luftwaffe got blown out of the air, but more often the UK built ship after ship only to watch them sunk by the Luftwaffe - so the main weight in this thrust must be done by the US.
If I may say so - Japan does not have to go after russia immediately, buiding up a potential threat to the US West coast is more important.
I do not say that teh Axis does suceed every time, but they really get a 50+% share…
In the games I played so far (slight Axis advantage) Lady Luck decided the outcome of the games. More than once by a single streak of bad rolls in ONE offensive, but also by some attition to one side by losing the more risky attacks, when probabilty would have sid otherwise.