I have two suggestions for solutions to the "OP" sniper artillery.
The first is that the command squad get the big artillery, and the sniper gets the mortar strike. Put a relatively long timer on the command squad's arty to make up for the fact that it would be even crazier. Then, if it still seems OP, make the artillery Tier 2 with charge tier 1 and binoculars tier 0.
Why would this be a sensible thing to do, you ask? Well, for one thing you can spam sniper squads all you want, but this way the crazy awesome artillery only ever has one squad spotting for it, and if you get a lucky shot on the major, the Russian player won't even get to use it. Also - and I know this is bad voodoo around these forums, but i'll say it anyways - it's slightly more historically accurate. Scouts were generally able to call for fire from a specific mortar battery each. Lack of trained (they were never hurting for untrained) personnel meant that the bigger arty was only in communication with the major's HQ (the command squad in this instance).
Now the other one is to get rid of the sniper arty, and let the sniper team get an ability similar to the Schwimmwagen's "Mark Targets" ability. Basically the idea here is to mark something so that your horribly inaccurate mortars or ATG's can reliably hit it it, which is less historically accurate, and less awesome than having artillery, but it could perhaps be used more often, and encourage multiple units with different roles to work together more.
