Major artillery and pin point should never be used in the same sentence. It's slow firing and inaccurate. Even if the target doesn't move before it starts landing(which there is plenty of time to do even for weapon teams) there is a good chance it will miss it's target entirely. Vet 2 adds two shells but your opponent has to be pretty bad to stay in the same place for even the initial 3 since there is a larger then normal time inbetween the shells landing . It's almost always a waste of munitions.
With veterancy it's perfectly fine to use on tier buildings and Pak43. That's really all you need to know on the major. As for mobile ranged units. USF has the best one in the game with the M8A1 vehicle. It's mobile, can smoke, can phosporous. I really don't think giving USF heavy arty, insane infantry, insane long range tanks, and AoE shell Jackson's is a good idea (Especially with talk of a pershing on the Horizon). OKW doesn't even have artillery and the axis artillery isn't that strong.