RE: Artillery dialogue
That would make a difference for short range HA fire against vehicles/units in fortifications, as SA fire is the same regardless of whether it's direct or indirect, and I'm not really sure if the artillery hard target modifier is applied if you fire within the hard target modifier range through the artillery dialogue.
Edit: artillery fire doesn't show a fire value, so I can't check whether the hard target modifier is applied at short range if firing through the artillery dialogue.
It might also potentially make a difference when an artillery unit fires through opportunity fire instead of indirect fire if the indirect fire modifier is anything else than 100%, like it is for the Allies in BoN. Opportunity fire is less effective than indirect fire. I'd have to run some test with on-map results turned off to see what happens to the fire effect in situations where the artillery unit can see the target and fires on the other side's turn.
One thing that will happen is that artillery units that fire when spotted have a chance to attract opportunity fire, including enemy artillery fire.