The Axis Player mod changes the weapons + soldiers: Germans to Russians Russians to Germans Americans to Japanese Japanese to Americans
I use other German flag skins in mine and I noticed that whenever I used a skin to change the German flag, every single german flag in the game also changes to the exact same flag. So, it stands to reason that if you start over and skin the german flag as the soviet flag and vice versa it will solve the problem the same way. The guy who made both these flag skins is called War_Crimes, maybe someone should ask him about this? I'm pretty sure this would work.
We don't really need to change the German flag's appearance. Just switch it with the Soviet one and vice versa. Although this is still cool.
The result would be the same. The only difference is, one works and one doesn't.