I'd say in the bigger picture for gameplay reasons the Suomi might have to be slightly more OP compared to the russian smg's because equipment wise the finns are going to be in a worse situation. While this doesnt apply exactly to Sammatus as the russians havent got such a massive tank advantage but for future maps it could be a problem. I dont know if it was intentional or not. I'd personally would make the finnish handheld weapons just tiny bit better than the russian ones just to balance out the fact that finns will most of the time fight as infantry, so to me it makes at least some sense if they got a bit of an edge in that area.
Also, finnish bias.
Sammatus might need some adjustments but I'd give it a bit more time before making any conclusions. Tobruk syndrome is a normal case that happens to many of the maps after they have been released.
Verta pakkiin, perkele.