The sound of inter-team communications is still dis-jointed. In Combat it is simpler and the whole premise is keeping Information flow maximum and cutting out nonsense, or things that raise the ambient noise level. ABC principle:-
The constant use of "Enemy Infantry Man - Direction" constantly repeated to cover all the members of the squad would never happen, it also makes the game sound mechanical and therefore unrealistic.
In PvP and multiplayer or CO-OP Multiplayer this is a huge issue and completely wrecks immersion and drives players to turn off Music and sounds in game to stop going mad with the ridiculous sounds and speech.
My suggestion would be to do the following for Team AI speak.
"CONTACT Enemy (delete as applicable) - Fireteam / Squad / Section / Vehicle - Direction - Range".
You would never say " one - Engage Machine gunner", you would say "Target Priority Machine Gunners" to the whole squad or Fireteam; not individuals within the squad.
Also the constant "Under-fire" / "Enemy Fire" is not really necessary, because Contact pretty much means you are into a firefight, unless it is a soft contact. It doesn't add to the experience and as a Soldier saying this your superior would slap you and tell you to shut up, because we know we are under fire.
It is a holdover from OPF which had to have it in order to work, but today with all the sophisticated systems and resources you should be able to make something more organic in feel, if not in operation.