Glad it helped. :)
Of course, besides the "Time more" from example above, there are more ways to trigger the action, like unit or group out of zone, or in the zone, even by using the comms menu...
Experiment, or ask if you need assistance. :)
Yeah, works fine for me.
The only time I couldn't communicate with my wingman was in some of the Viggen's missions. Resaving in the mission editor fixed the issue.
It seems they are not attacking because of the night time. When I changed the time to daytime, helos attacked, infantry returned fire.
One other thing, IMO it is better to have the last waypoint (the one with the attack action) to be further away from the target, gives the AI more time to prepare for attack. But in your case that my not work because you want the helos to follow the terrain...
You can add "Attack group" advanced waypoint action to the choppers, like on the screenshot. The ground units should fire back on their own.
No need to mess with ROE etc for a simple attack.