happened in annexed parts of Ukraine during "referendum"
I assume they instead did the more normal things of local voter intimidation, outright not counting, and lying. If your government doesn’t want to follow democracy you’re fucked either way. No need for armed gunman to make you vote at gunpoint.
That was political theatre being made in a conquered territory, not an actual attempt at democracy. It’s like pondering the specifics of a vehicle’s engine performance/efficiency after it’s been hit by a fucking train.
There was/is no solution to fix voting problems in Russian held territory other than to violently force Russian thugs to leave.