I don't know how to handle your scenario but as for the different countries you mentioned there could be a couple of things that could happen.
As for Sweden, the communists were never going to take power in Sweden as things were far too stable to allow for a communist takeover and they only amounted at their peak in 1944 to 10.4% There could however be some Finlandisation or soft influence from a communist party that is better set to influence policy.
Speaking roughly there are 2 big things that could have been different. A lack of a communist split off Inside the communist party SKP in 1929 when Karl Kilbom and most of the members were expelled from the Comintern, and several members left the party. Kilbom, together with Nils Flyg and the party majority, ran his own SKP. Sweden now had one SKP in the Comintern and one outside. The Comintern-loyal party was reorganized and led by Hugo Sillén and received three percent of the votes in the 1932 by-elections, while the old Communist Party led by Kilbom received 5.32 percent. World War II was another difficult period for the party. SKP was the only political force in Sweden that supported the Soviet side in the Finnish Winter War and was the only parliamentary party that was not allowed to sit in Per Albin Hansson's coalition government. Like the rest of the communist movement, the SKP in 1939 made the analysis that the war was an imperialist war, an analysis that was largely characterized by the Molotov-Ribbentrop Pact that the Soviet Union signed with Germany. Remove the Finnish Winter War, or make it so Finland accepts a land swap deal. Invasion is necessary here, but I think they would be safe because of Britain and the US controlling the seas and you have to cross the baltic more or less to get to Sweden.
Speaking of Finland they could easily have lost the Finnish-Soviet war if they were a little less lucky, or the Soviets pushed on another week or so. They could have also caved to Soviet demands for ceding borders, only to then be invaded from less defensible borders. Finland basically did the best possible thing they could. They tragically lost a bit of land, but they didn't suffer the same fate as the Baltics.
Spain could probably have become communist during their civil war with a bit of luck and actual Soviet support. As it happened IOTL the soviets basically left them to die as they offered an alternative version of communism.
Ireland: no chance without Britain also becoming communist. It will not be tolerated, and can easily be done.
Of course things would be different in this timeline but I am trying to use this as a baseline.