Краткое резюме для англоязычных:
I am confident that "Stalin's Rosa" was a pure invention of Russian anti-Communist exiles. As I recall "The Rosa Kaganovich Hoax" story has been first traced to a White Emigration magazine in 1932, when the xenophobic exiles observed career rise of Lazar M. Kaganovich and re-purposed both the Protocols of Elders & the biblical take of a Hebrew patriarch putting his wife into the beds of kings and pharaohs. It was just too hard to resist adding a most common Yiddish names like Rosa or Sarah, and Lazar's surname, to get a bestseller story of the Jewish mastermind controlling Stalin like a puppet through an evil seductress. So the Rosa tale caught on. The Nazi's put it to heavy use, and some Soviet defectors cited it. But as far as I know "that Rosa" never existed.
And in fact Lazar Kaganovich was no mastermind. Not even an effective administrator. True, he was slavishly loyal to Stalin and utterly devoid of morals, and his master kept him alive and employed despite many failures for the likes of which others in the elites have paid with their jobs and lives. Stalin kept finding him other jobs after Lazar botched the previous one, or made so many enemies as to lose effectiveness. Lazar's latter job assignments were decidedly unimportant, and the final years of Stalin's rule he was but a Mister Nobody.
But the fictitious Rosa, with all the Western and defector stories about her, was quite important. The Nazis tortured prisoners to learn more about her, and the Soviet security organs were in hot pursuit of the Rosa rumors (and Lazar had great many enemies in the old USSR, especially in Ukraine). So the "Hoax Rosa" impacted the life of my very real Rosa Kaganovich quite severely.
Rosa Kaganovih Rutman in my family was 13 years older than her nephew Lazar, and couldn't stand him. But she was close to Lazar's older brother Michel / Michael, who was the first socialist in the clan, and he held relatively high ranking jobs in the USSR, until he was killed (or forced to commit suicide) in one of Lazar's enemies unsuccessful attempts to bring down Lazar by making his friends and his kin share dirt on him. In Michael M. Kaganovich's final years in life, both he and "my Rosa" lived hundreds miles East on Moscow, and continued to meet in person, and she kind of blamed herself for Michael's death.
A few things about life of Rosa Kaganovich Rutman. Her husband Aron Rutman was a blacksmith at the same birch-tar factory in Varovichi where most Kaganovich males also worked (the Kaganovich home village, then called Kabany, was about 5 miles down the road from the much bigger hamlet of Varovichi). When the economy collapsed in the wake of the 1917 Revolution, Aron made living by selling his wares around the county. He was killed by robbers on the way to one of the local fairs. Their older kids were also blacksmiths by then, and they went to the city to earn living at a factory. The Rutmans settled in Ekaterinoslav, later renamed Dnepropetrovsk in Ukraine. But in the height of the Great Terror of 1937 / 1938, someone was digging for the dirt on Lazar, and his Rutman kin ended up in the cross-hairs. Luckily, one of their friends knew, and whispered to them to leave ASAP. The Rutmans went to Siberia to work at the upstart heavy industries there. Rosa's youngest, Eli, worked in the famous "Tank City" of Chelyabinsk (and then married into my Pruss family). Rosa died in 1947 and is buried in Chelyabinsk. Alas, I can't find her grave yet. I'm close to her granddaughter Raisa (named after her ... both names are versions of Yiddish Reyza "Rose flower", and in the surviving vital records, Rosa Rutman is actually called Reyzle or Reyzya). So their biggest family legend was that Rosa was trying to talk Michael into dropping out of the official life and moving to Siberian hinterland, like she did, to stay alive. Instead, he went to Moscow to petition Stalin, and it was the end of poor Michael's life
I need to add that there was also another Rosa Kaganovich in Lazar's family as well, 38 years younger than "my Rosa". It was a common name! "The other" Rosa I. Kaganovich was Lazar's niece. She died last year in New Jersey, just shy of 100. Her grandson is the (relatively infamous) Boris Epshteyn, a onetime Trump's communication man. The younger Rosa isn't the one from the hoax either; she was just 16 when the supposed seduction of Stalin happened.