Does FC2 not simulate a ground FAC or an air FAC?
Not really no. Its going to become a major part of DCS:A10 and likely part of Black Shark too, but probably not for FC2.
In the mission builder, I see that you can place a static object that is marked as a ground FAC. And you can assign an aircraft to act as an Air FAC.
But they don't seem to work in the game? Am I missing something?
The role selection is basically a filtered list of payloads and aircraft available. The AI flying as different roles will act slightly differently. However the AI don't have enough intelligence nor a way to communicate with the player to give target information.
Is there a way to contact them?
Nope. A-10C will have built in functionality to use radio messages to trigger stuff... but its still all pre-programmed via mission triggers.
I come from the Janes FA-18 community, where the Air FAC and the ground FAC both interact with the player's flight, through radio comms. This sim doesn't have that, I take it?
The best we can do is to repeat a triggered message until a new target comes up or you take care of it.
In that Warthog Day mission, they have just prerecorded message assigned to different units, is that? I see how that is done in the mission builder, but that is pretty weak.
How does it work in Black Shark?
Its the same as FC2 right now. Currently the editors and functionality in both games are identical. Black Shark just has all the extra stuff that is simmed for it. The editor is pretty basic, but pretty powerful. If units are stationary its pretty easy to have the a triggered FAC. Once they start to move things get a little more complex and annoying.