If Japan doesn't invade China in 1931, what things would change. There wouldn't be an american embargo on Japan, which means no Pearl Harbor. US won't join WW2. However, Soviet forces eventually defeat the Nazis, and they control all of Europe. What will happen from there?
Working with the OP, and its assumptions, here's what I've got.
British and Soviets get increasing American subsidies for their war efforts, 1941-1945.
Soviet-German battlefronts operate similarly to OTL up until November 1942.
The Soviets still encircle and crush Germans in Stalingrad in early 1943.
But, without the combined bomber offensive and combined anglo-american west med amphibious ops and overlord threat, the recovery of Soviet home territory, and the Soviet penetration to lands west of the 1941 border, is slower going than OTL.
The British wrap up North Africa, including the Vichy territories, by January 1944.
The Soviets penetrate deep into Poland and Romania in 1945 instead of in 1944.
The British do invasions of the major mediterranean and Aegean islands through 1944.
In '45 they get into southern Italy, Greece and maybe northern Norway.
Ever building Soviet pressures from Poland against the Reich, supplemented by additional Soviet advances through the Balkans, compel ever-increasing German troop transfers from the western occupied territories throughout the 1946. And those transfers do not arrest steady German gains.
By early 1947, the Soviets are occupying Vienna, Prague and Berlin. Hitler's HQ is moved to the Ruhr or Swabia. Forces in France and the Netherlands are increasingly denuded. Resistance movements, largely communist-aligned, but not entirely, increase their size and activity in France and Italy.
The British in early 1947 invade multiple places in western Europe (in France and the Low Countries) against the weakened Germans and in collaboration with the local resistance forces of all stripes. Meanwhile, the Soviets drive through the Fulda Gap and through the Main river valley to reach the Rhine.
In the ATL's version of Yalta, the British have a symbolic occupation zone along the northwest coast of Germany and maybe some of northern Rhineland, and the Soviets have recognized British interests in Greece, the Low Countries, Norway and Denmark and Italy and France to some extent.
However, non-communists in France and Italy need to "co-inhabit" governments with communists. The Soviets control the lion's share of Germany and all of Austria. These are made into "People's Democracies" under Communist Party and Soviet control. Only in Norway, the Low Countries and possibly Denmark, if there has been a late British expedition there, can the British consider the local governments both "reliable" and democratic.
The Communists are on a clear trajectory to power in France and strong in Italy.
The balance of power is vastly in favor of the Soviets, but, being exhausted, the Soviets are not into launching direct military aggression to remove remaining outposts out of their control. (Although an interesting twist might be heavy Soviet support for insurgency and threats along with a communist France, against Franco-ist Spain. The Soviets use heavy-handed diplomacy, control over German territory, control over local communist parties and reparations and control over liberated PoWs in their custody to get their way on most disputed issues like Iran, the straits and the eventual governments of Greece and Italy and France.
Franco-ist Spain is the main European target of Soviet pressure in the late 1940s and the Soviets support all manner of anti-British movements in the colonial realm.
Japan is a locally strong semi-democracy with significant trading ties to the US and British Commonwealth as well as the Soviet Union and China. In his more aggressive moments, Stalin contemplates a war with Japan to reverse the verdict of the Russo-Japanese war, but its likely he does not see direct aggression as worth the cost.
Rather, the Soviets at most harass the Japanese by sponsoring Korean unrest and insurgency.
In China, Chiang Kai-shek has consolidated control of China and eliminated communist pockets and recalcitrant warlords through the 1930s and the 1940s, taking advantage of not being in a war with Japan and the Soviet Union's preoccupation with the long Great Patriotic War of 1941-1947. Chiang by 1947 has control over all the territory the Qing Dynasty held in 1911 except for Outer Mongolia and Tannu Tuva. Remaining armed Chinese Communists ultimately were compelled to retreat to Outer Mongolia.
Chinese and Japanese manufacturing both developed and supplied a variety of light and low-end industrial goods to the Soviets during the war, which were often paid for by US dollar loans or advances.
After victory in Europe, the COMINFORM may renew attempts to revitalize communist agitation in both Chinese rural and industrial zones, and may be willing to support reinfiltration of PLA veterans back into China.
Soviet propaganda vigorously promotes the independence of European colonies in Asia, and Japan, China and the USA agree with that basic goal. But the latter three hope to avoid the Soviets and Communist aligned movements being the main beneficiary of change. The Japanese have the most resources and interest in subsidizing alternative political actors in southeast and south Asia.