A recommendation - if you want the AI to make true strategic decisions that make sense, you need to be able to assign unoccupied (by you) foreign territory to theaters. This will allow the AI to understand what you want it to think about, and what is not in the cards. Under the current system, you might have three or more theaters as Germany facing the Soviet Union. What balance of forces will be appropriate for the theaters? Only what is on their front? This leads to silly decisions when your intel can give you much greater detail. Also it would prevent silliness from happening like in one my Germany games where I had invaded the US in the NE and had gotten bogged down. I wanted to land another Army Group in the S. US to break things open. So I gave the AI that objective. What I got was that AG funneling through my already overcrowded NE beachhead. Carving out another theater on US territory would allow the AI to know that I wanted AG Dixie to attack Georgia and into Tennessee, while AG NE continued the assault into Michigan.
Another nice-to-have, would be then to assign sea spaces to theaters in the same manner. That would allow the player to assign a defensive ground theater, and an offensive naval theater. Think the US in the Pacific. You had the Western Pacific, SW Pacific, and CBI theaters. The first two looked identical at the beginning of the campaigns, but the their ultimate objectives looked very different (W. Pacific stayed small island, SW Pacific transitioned very quickly to protracted land engagements on larger islands like New Guinea and the Philippines).