I think the split makes Japan’s efforts against the Brits much less meaningful. In AA50, every one of those islands or territories in the Pacific that the Brits lost directly impacted their ability to fight the war against Germany/Italy. And this in turn drew US response to try and protect those Brit assets as long as possible (to keep the pressure on Germany mounting).
In Global with the split resources, the ‘Euro-Brits’ don’t give a fig about the money Japan is taking away since it doesnt impact what’s going on in Europe hardly at all. So they are less pressed to have the US protect those resources and thus the US cares a lot less about the Pacific other than making sure Japan doesnt go completely hog-wild.
It kind of feels like you’re playing the two games side by side rather than having a more integrated total war feel that AA50 had. We really enjoyed the game overall, but there was a lot less of the cross-theater assistance/interest since the two theatres have such minimal impact on each other.