You say “Let China be” but remember they can capture Hong Kong and Shanghai. Thus even if Japan was to take Calcutta, its work would then have to take Sydney and Honolulu, with its navy. You think America is going to sit by and let you do it, in Global? Ha ha.
France/Japan political situation - rule clarification
The 2Ed and Alpha +3 rules say:
A state of war between Japan and France or between Japan and the Soviet Union will not affect relations between Japan and the United States, and vice versa.
Japan may attack French territories at any time, requiring no declaration of war against any Allied power before doing so.
If Japan attacks French Indo-China, does that affect relations between Japan and UK/ANZAC?