Welcome!
One thing to keep in mind is that the Axis only need to win on one side of the board.
This means, that if a Japanese strategy is good enough, even if Germany gets their butt kicked the Axis might still be able to win if Germany buys enough time for Japan to win.
It’s still risky, of course, as an increase in IPCs on the Europe board can translate to an increase in units in the Pacific, but it’s an option and a far more viable one than the equal version for the Allies.
Personally I’m not a fan of J1 or G1, but that is more out of principle than practicality.
I found this cool J1 video:
https://www.youtube.com/watch?v=fRi3aIsj8P8
Important note about this video:
There are some astericks in the video, and it is not explained what they mean. I have gotten information from the maker of the video what they are, however.
The only thing that can/will stop this J1 attack is if the Soviets stacked all 18 infantry in Amur.
In that case, both I and the maker of the video strongly advise not to do this strategy (I learned this the hard way, trust me, it’s painful to watch). I recommend, if the Soviets declared war, to attack that stack. Air units, landing back, can defend Jehol and Manchuria from the Mongolians.