We all know the only necessary voice command is ACHTUNG! SHAMBEH BAMBEH!
But seriously, I think this issue is already covered with more specific voice commands.
If you say you didn't penetrate, what is that telling the driver? Maybe your tank has a really ****ty main cannon that can't penetrate frontal armour of a panther at the range you're at, so you either need to get closer or move round to get their side/rear armour.
I think if there's going to be penetration related voice commands (heh), then there should be two specific ones:
1. "We can't penetrate at this range!"/"We can't penetrate their frontal armor!"
2. "We can't penetrate at this angle!"
Which gives the driver more specific information on whether to try to face the armour square on, or to manoeuvre to the side armour.
However, even that seems kinda clunky when you can just say forward, left, right etc.
What I think it would be cool is if the gunner/commander could hit a button to check ammo, and then have the AI loader shout out "15 AP shells left!", or whatever the actual number is. Or at least have this option in Realism, and allow hud ammo for relaxed realism.
This seems to be both more realistic and more natural whilst removing hud. If the hud doesn't tell you how many rounds are in a magazine and you just get "magazine is heavy", it seems to make sense you should get something similar in a tank, especially when the role can be given to an AI loader (which makes the death of the loader more important).