The most deaths (likely) ever produced by Soviet/Russian Air Defense happened subsequent to 28 May 1987. However those deaths came from within the Air Defense establishment when a West German amateur pilot, Mathias Rust (18), landed a Cessna 172P near Red Square, having flown from Helsinki, Finland to Moscow, USSR. He WAS detected multiple times, but as a single, obviously light aircraft blip, the missile defenses never got a ‘fire’ order!
It is speculated that the ‘egg-on-face’ resulting from this stunt enabled Mikhail Gorbachev to remove several key military opponents to his liberalization efforts (perestroika). Rust was arrested, tried and sentenced to 4 years in labor camps. However, within a year, Gorbachev and Reagan signed the Medium-Range Nuclear Missile Treaty and Rust was released after 14 months of jail.
Systems are only good as the personnel and training that controls them. No one will tolerate a system that fires automatically and thus there are always ways to spoof and penetrate while the opponent is paralyzed by doubt!
You forgot to add maintenance to your list. The Soviets, and now the Russians are notorious for their neglect of preventive and periodic maintenance. You can build the best systems the World has ever seen, fail to maintain them though and they might as well be paper weights.