When tasking artillery units to fire at a point, they do so instantly as long as that point is within a radius of 4km. When the range is over 4km, a delay is applied based on skill level.
I have tested this with a couple artillery units and they all seem to use 4km as the cut off point which seems very arbitrary to me.
Is the delay maybe meant to scale with range? Because as it stands, the delay is the same for any range between 4km and the artilleries maximum range.
I have also tested an MLRS unit which has a minimum range over 4km, and the delay is applied to it too.
Ideally the delay would get removed completely and left up to the mission designers wishes.
Attached is a mission file with 2 M109 artillery pieces, one of which has a target point just under 4km and the other one just over 4km. You can clearly notice the delay in firing.
artillery_bug.miz