I retract my previous comment. Russia's last peak predated SA's Omicron peak, and the high fatalities would certainly indicate their previous wave was Delta. (Like some other countries, Russia's data indicates Delta's CFR among the unvaccinated was higher than "original COVID's" CFR among the unvaccinated. But, that's a separate discussion.)
I would expect Omicron's fatalities to be lower in Russia than Delta's were. BUT, their equivalents to ER's and clinics will likely be swamped with moderate cases. Russia has had almost no "breaks" in high case numbers for over a year - their health care workforce must truly be exhausted...
“ Russia’s last peak predated SA’s Omicron peak, and the high fatalities would certainly indicate their previous wave was Delta”
My impression is that the worse the Delta wave was in an area, the milder their Omicron wave will be.