Couple of problems with this. I’m assumming you dont use your airforce to kill the British navy or backup Africa? What happens when Britan pops in 1 figher and some inf every turn? Or better yet, T1 you get 4 British inf into WE, then America 2 inf, then its a pretty even battle for Karelia, with odds to Russia. Then, after that, America, with its 3 Trn buy, puts 6 MORE inf into WE, then Britan puts its buy into WE. Bottom line, your plan would fail.
No offense, just attack Karelia before T7 is hard, if not impossible.