"Czar" still used in Soviet mode

[JuEeHa]

On 15th of March 1917, Czar Nikolai II abdicated in favour of his brother, Grand Duke Mikail Aleksandrovich, who refused the throne.
The Petrograd Soviet was established in March, and existed for a brief period when Russia still had a Czar in power, but at the time it shared the power with the Social Revolutionary -lead provisional government.
Generally speaking, Soviet Russia can be seen to start with the November revolution, 7th to 8th November 1917. Nikolai Aleksandrovich was still alive (his execution by the Ekaterinaburg Soviet was in 17th of July 1918), but he was no longer a Czar.

Therefore, another term should be used. I suggest "Comrade"