Very sorry to hear these people entered the Soviet Union during the reign of Stalin. Poor sods.
Yeah...the North American Finns in the Soviet Union were very ill-fated. This migrant movement is very special one, maybe unique. It cannot be defined clearly why this event happened, many of these migrants were living in rather comfortable circumstances in the United States and in Canada, they had their own houses, own cars and their children were educated under the American school system. In short words, they were living ordinary American life.
But there are some certain reasons why 10 000 North American Finns left the New World for the Soviet Union. One important fact was the Great Depression in the U.S. and this of course influenced on the Finns. And not all of the Finnish migrants had found "the American dream", many were living under the standards of living. Additionally it's known, that the ideology of leftism(socialism and communism) was very common among the early 1900s Finnish migrants in North America and it is possible that they were victimized 'cause this way of thinking. Also the crops were plaqued in many years because of the inland dust storms in the U.S. and this irritated the Finnish farmers.
Lastly must be mentioned the recruitment. This activity was systematic and organized by the Soviet authorities. They had recruiting officies in the large cities of the North America, like in New York and Montreal. There were the practical things organized, like buying tickets for the ocean-liners and trading property. Speeches and gatherings were commonly held in the Finn Halls, all over the cities of the continent. In the 1920s and 1930s the Soviet policies included to heavily develop the industry in the Soviet Karelia and make it a perfection land for socialism. The Soviets needed workforce for this plan and the Finnish American/Canadian lumberjacks and miners were considered as "cast-iron" professionals.
If the life had been hard for some of the Finns in the New World it was a disaster in the Soviet Karelia. There was absolutely nothing ready for the living, shantytowns and misery. Those who had managed to bring money or other fortunes with them were robbed, passports were collected and the American citizenship was lost, so the Soviet authorities told.
Thanks for the years of hard work a few Finnish settlements flourished in the Soviet Karelia. They were completely self-sufficient with some stores, shops, farms, housing and education systems. But this era of welfare lasted only for some years. The Great Purge ended the migration of the ASSR. The Finnish North Americans were executed and forced to work in the Gulag Archipelago. It is likely that some of the North American Finns joined the Red Army when forced to do so and eventually attended into the Winter War and the Continuation War against Finland in the ranks of Red Army.
There are documents of the Finnish American/Canadian survivors from the post-war period. They succeeded to escape from the Soviet Union but they did not to dare to stay in Finland because in the post-war era the Soviet Union influenced in the Finnish politics and the migrants feared that they would handed over the Soviets again. So, they tried to continue the journey to Sweden and managed to do so. Some came back even to Canada and the United States of America.