I loved the show, but in retrospect, the premise of 2 Soviet spies being the most prolific serial killers in the history of the DC area without being caught is a bit weak.
It's estimated there are 25-50 serial killers active in the US at any given time. There are also around 6k new unsolved murders each year. The point is that a murder done by someone with no connection to the victim is very hard to solve.
I mean there are several stories of these deeply implanted KGB sleeper-type agents in real life. Sure, not serial killers (who knows), but everything else is quite authentic.
Masha Gessen did some work on making the spoken Russian be more authentic https://www.newyorker.com/news/our-columnists/translating-th... ( She must have given up on Keri Russell )
Peter Jacobson (FBI Agent Wolf) appears in comedy Russian TV show inspired by the Americans "Adaptation" https://www.poconorecord.com/story/entertainment/2018/05/26/... . I've seen episode 1 available on the internet, full series is hard to find.