Hello Thomas Channel 6290 is quite intensively monitored by me due to the transmissions of pirate stations. I remember that it is assigned to SPA Gdynia, but in the past year I observed only 2 or 3 of their voice activities during the day time. I also noted the 3827 USB channel. It finds no regularity.
Unfortunately, I didn't pay enough attention to digital broadcasts.
I think you accidentally used Russian names in the examples you quoted:DIMITRIJ 59, ANTON 74 or TATJANA 77 .
Poles certainly won't say that - they use English letter codes according to NATO standards,
or Polish names such as Dorota, Adam, Tadeusz.
Let's call them "non-operational" troops use names that are nouns (sometimes very unusual) and one or two distinguishing digits as callsigns.
The HF ALE and MIL-STD 188-141 system is a great technique but remains outside my practice.
However, I will keep watch!