The Soviet Field HQ ability is still broken on every single possible level imaginable . Huge buildings can be converted to a field HQ and have no chance of being destroyed until very late game and by then it is often too late. It is the most cheesiest ability in the entire game, requires no skill whatsoever, is risk free and cannot be balanced as the ability is fundamentally broken especially in team games.
I cannot see a way around this but to remove the convertible building altogether in favour of only the buildable hq that is actually destroyable early / mid game..
I dont know because it depends on a game mode and the map entirely. Plus you can burn it to the ground by going double flame pios and working with your team mate. This commander is barely used in 1 v 1.