Those same Russian air-defence systems proved themselves effectively useless against the F-117 in the Balkans
There's been some improvements in the past 20 years too, sometimes even not only on paper.
Anyway, the biggest problem of the ex-Soviet militaries is their incompetence, not their tech. The systems employed are up to the necessary tasks and sometimes more adaptable than NATO systems, it's just that even their normal operation sometimes can't be achieved by people using them.