There is an unrealistic thing in the game already that British communists are going on a decolonization route in a sense that they give away autonomy to colonies. This contradicts historical behaviour of communists which always meant centralization. Decolonization would be okay but in a sense that communists integrate the colonies into the empire and rule them from the central government. This would mean annexation in game terms. The Soviet Union was ruled all from Moscow, just like FR Yugoslavia all from Belgrade. Communists giving away autonomies is like what the hell???!
I think the intent is to reflect the anti-colonialist attitudes of Communists. Most Communists outside of the UK wanted to see the British Empire broken up into it's constituent parts so that the locals could be free to govern themselves (as long as their government was Communist, of course). I'm not sure how Communists inside the UK felt about decolonization, but it is worth pointing out that while many Communists looked to the USSR as the "heart" of international Communism, many didn't agree with the ideas Stalin was putting forth, and hewed closer to Marxist-Leninism, or some other version of Communism. I think it is a safe bet that, if Communism had actually taken hold in the USA or the UK, it would look noticeably different than Communism in the USSR or China.
I think a better path for decolonization in HoI4 would be for the results to differ based on what ideology you are when you start the process. Currently, the UK is Democratic when it starts breaking up the Empire. As soon as the Dominions get independence, they leave the Allies and start watching movies on the living room sofa. This leaves the UK with all the newly released territories. Once decolonization is complete, everybody gets a random % roll to see if they stay in the Allies or form the Commonwealth faction (with the former Dominions usually forming their own faction, too) or go fully independent. That's fine, I guess, for a UK that starts decolonization as a Democracy and intends to stay as one as well, but I wouldn't have the Dominions be so quick to flee the Allied faction. India, yes, but not Canada or Australia (especially not if the Aussies and the Kiwis have fascist Japan stomping around the Pacific).
A UK that starts decolonization while Communist (which I'm not sure is even possible currently... I haven't gone down the Communist path as UK and the AI always starts the process as a Democracy) should have all the Dominions leave the faction (they start with enough autonomy that the UK wouldn't be able to realistically influence their ruling governments into flipping) and all of the newly released territories remain in the UK's faction, with no % chance for anyone to leave. This would turn the Empire into a Communist Confederation, where the member states are all equal in status, have full independence, but remain linked politically and militarily. It would also confer the protection of the UK's MIC and military over the member states while they bring their own industries up to speed. Right now, Communist UK dismantles the Allies faction once it goes full Communist, which leaves the game with a faction comprised entirely of very weak members, all of which are tiny and easy to capitulate, and one fewer country to offer guarantees of protection. Someone who waits for the UK to go full Communist before starting to expand can eat virtually the entire former British Empire in a single stroke (the faction has few, if any majors, so mass capitulation becomes the order of the day) with only France likely to try and guarantee anyone's independence.
