I don’t know if I like it for the Allies.
As Japan I would bring the 12 units from Korea and Manchuria, 8 planes from Japan and SZ 6, the four planes from Manchuria, the fighter from Korea and the one from Okinawa. I’d also transport an inf and tank from Japan and take the bombardment hits with a BB and C. Kiangsi hits Hunan and I’d hit Yunan with the standard 4 units, fighter, tac, 2 strategics. The battle calculator says Japan should lose 8 inf (already took off one fighter from the AA guns). Virtually all of the planes can make it back to Jehol, ensuring Yunan is still reachable turn 2.
Japan is now in fine shape. Turn 2 they send an infantry to Siberia and the remaining 3 or 4 units to Buryatia (including a blitz through Sakha of course) and they just roll from there. Those 6 Russia inf aren’t much threat (and if Japan wants to be aggressive they can hit Buyant-Uhaa turn one with the Jehol units and the mech from Manchuria. Taking 1 inf from the Amur battle has no effect). Russia is no longer a threat in the far East and Japan is making an extra 6-7 IPC’s as early as turn 3 (while Russia is losing that much).
So how does this affect the conflict in South Asia? Imo, it doesn’t really. You can still hit Yunan round two with most of the Japanese planes; Japan can build a complex round 1 in Shangtung to compensate for the lost men up north and reinforce Kwangsi with men from Japan (or even forgo the Hunan attack and send those 4 troops to Kwangsi as well). Hell, if you want to get crazy Japan could build a complex in Shangtung and Shanghai then follow it up with 3 arm, 3 mech turn 2 and completely lock down the area.
My plan slows Japan down for the first couple rounds maybe and definitely prevents a JDOW1 or even a JDOW2, but I believe it’s a win for them in the long run. I only like the Amur stack for the allies if America is committed to a KJF.