When you hear traffic on 8345 or 12464 look for the other side of the duplex channel on the following freqs;
RIW Moscow sends to ships on 9145, 11000, 14556
RCV Sevastopol sends to ships on 15586 day and 7566 night, with weather reports also on 5915, in the past on 10543
RIT Murmansk (artic circle) 5343, 7467, 11155
RAA St Petersburg 8120
RJS Vladivostok (pacific coast of Russia) 4048, 5411, 7632, 10203, 13636
RIW, RIT, and RCV are the most commonly copied hq calls heard here, so whoever is called by the ship being monitored, look for a response to their call on the designated channels.
The top two are also the most likely to be heard here due their locations, I don't expect to hear RJS Vladivostok (means something like Ruler of East) at all for the most part due the distances and would be surprised if I could hear RIT Murmansk.