Thanks.

I've been having this particular issue with artillery firing subordinates since as far back as A2:OA. It seems to be present for any instance of AI controlled - player issued fire mission orders to subordinate/on-map units (waypoint or just in-game command). The support module itself doesn't seem to have the issue but I'll admit to not having extensively tested the support module for on map units due to the complexity of setting one up in the editor to use on-map units rather than off-map/virtual units.