POD is the 1919 revolutions end with socialism extending to the Rhineland. France, the UK, Italy, Japan, and Portugal formed the League of Free Nations in response, with the U.S. as an allied non-member.
The Second Great War (1942-1946) ended with France, Italy, Spain, Belgium, and much of the Balkans being inducted as communist nations. Great Britain was weakened and forced to accept an armistice after the Soviets successfully backed the Indian independence movement.
China (not under Jiang) lost Manchuria in 1931 and was invaded in 1937, only barely managing to throw together a United Front with Soviet and German support. The U.S., which remained neutral, contributed via a limited Lend-Lease. Japan was eventually pushed out of most of the region, but exhaustion meant the Chinese were forced to stop on the Manchukuoan border. French Indochina was annexed by the Japanese after Paris fell, but this action got them kicked out of the LFN. The Dutch East Indies remain in Dutch hands since the Netherlands retain their neutrality.
I don't want to be too harsh on this but it kind of comes off as being veyr lazy with East Asia in several ways. While Imperial Japan did see itself as a leader in East Asia after the First Sino-Japanese war, outright war and conquest was never really a part of the plan, not to say that Japan ever really had any plans in that regard. What happened in 31 and 37 was more elements of the Imperial Japanese Army acting on their own and The government in Tokyo generally giving assent and going along with it after the fact. But even there You didn't have militarism take over or at least the extreme elements and they only grew with the Great Depression of 1929, There was still at least a chance with Taisho democracy.
But this becomes a question of what do you do with Japan's political situation? The Imperial Japanese military was kind of a mess of competing factions but a full-on defeat from the Second Sino-Japanese War it's kind of hard to trace what could happen. While the more radical Imperial Way faction was mostly crushed during the 226 incident some of its influences still lingered on, A full-on defeat and what its social and political implications could be for Japanese Society could be anyone's guess. I also take it that somehow in some way Japan's still going to be this diplomatically isolated nation?
But there's a whole other question to consider with what are you doing with China. First and foremost the Japanese invasion of Manchuria was more Japanese actions against one military clique than invading an entire country. But there were outcomes where at the very least a less Cliqish China or Northern China was possible, Basically there's a wide range of outcomes from a 1919 pod That I don't think can be brushed aside, but any China that's in a better position for either 31 or 37 is going to be more than willing to demand Manchuria back. Especially when in OTL If Japan is being driven back through a land War then out and out surrender they're not going to have the means to hold on to
any parts of China give or take Taiwan.
To say nothing of the fact there's a whole slew of political situations that may or may not be in play depending on what the Soviet Union does with China. The Soviets were the inheritors of a lot of Tsarist colonial interests in the East. The Chinese Eastern Railway in Manchuria, Mongolia and resource exploitation in the Xinjiang region were these interests. The question of Sino-Soviet relations is going to be important and that depends on
if the Soviets are as antagonistic as they were, especially when Outer Mongolia, Xinjiang, and Tibet are all going to be seen as a part of the concept of China no matter who is ideologically at the wheel.
I feel that you're Pacific War scenario doesn't make a whole lot of sense. the thing with the Pacific War is that the Japanese decision to attack Pearl Harbor and subsequently declare war on Britain and France Is that it was an outgrowth of the Second Sino-Japanese war. the Second Sino-Japanese War was less a planned war and more a border skirmish where neither side wanted to back down. Jiang could not afford to back down because it would be a serious loss of face and he was already held hostage during the Xi'an incident. it was a war Japan had no real clear objectives with other than 'win' whatever that was supposed to look like and the resulting mission creep is basically what defines the entire conflict.
When France is in trouble Japan decided to make demands to try and cut off supplies from Indochina to the Nationalists but that went from demands to an outright Invasion due to a Japanese unit forcing the issue. When that escalated to an American oil embargo that's when Japan considered Pearl Harbor, but what you have to realize is Japan's basic plan was this: Strike Pearl Harbor and banked on no European meaningful interference for a while, so take the resource-rich areas and use those resources to win the war in China which had ground down to a stalemate and from there trying to negotiate a settlement. The idea of a Greater East Asian Co-Prosperity sphere was something that was tacked on later on and while Japan decided to expand its war from China to all of East Asia, if Japan is only taking French Indochina there is not much of Greater East Asia Co-Prosperity sphere to go claim, if at all. Especially when Japan is still in the relative good graces of the Diplomatic community and not at all in a situation where its only real allies were Germany and Italy.
I don't think you can get this yellow peril-esque premise of a hyper-aggressive Japanese empire in the 60s, with a greater East Asian co-prosperity sphere that's only Japan, Indochina, ( which really could be separate) and Thailand as an independent member. Japan's military resources have taken too much of a beating from the sino-japanese war and even without any serious damage to their World War II Navy Trying to renew a war against China is much riskier this time around you probably have American fleets in the Philippines and Pearl Harbor that make the necessary naval maneuvers that Japan needs very risky You're not even going to get this grand war against a superpower but a quick war against the Japanese. To say nothing of the potential naval evolution that the Battleship was on it's way out, and due to the OTL Washington Naval Treaty, Japan was already working with carriers. Yet even without Nukes, the Japanese Navy might have to evolve in ways that make conventional warfare very difficult, to say nothing of the Army.
Don't get me wrong, a surviving Imperial Japan into a Cold War situation can always work but it requires answering some very tough questions that aren't easy to track. Bamely what would happen to the political situation of Japan post-war? Would Japan find itself as more of a useful Ally to one power block or the other, just because I don't see isolation as a possibility. Does Japan try and aim for a softer approach by backing decolonization movements where it has to do perhaps a little more than pay lip service to the ideas of liberation? I feel like if you want to do the story idea Justice you have to do more with East Asia as a whole than just a bunch of butterfly Nets where everything post 1919 just happens in the same way Or if it doesn't happen in the same way you get some bizarre looking outcomes from it.