So why does this matter if they are Russian? The FBI can’t really touch them but if they’re ever on American ground, they can be arrested. They will not be able to travel outside of pro-Russia countries without the risk of being extradited, and they will not be able to access any assets in the US. Putin is unlikely to extradite them.
It’s likely just a way to rattle cages and create unrest among others that conspired. I don’t know how high on the chain these people are but it’s also likely to rattle Putin as well. Putin rules only because he lets the oligarchs make money while he turns a blind eye. Sanctions hurt the oligarchs so if Putin can’t remove them or keep them unenforced they (the Russians) will install someone they think can.