Sorry, somehow missed the comment regarding the scott/pak.
Anyway, as for the other indirect fire units - yes, they all need addressing in order to keep things 'fair' between the factions. My original post suggests this, but also points out that because of OST's 4-man, high cost squads, they are currently the most affected by this issue.
"Currently affected most by this issue" ?
As said before the mortars have already been nerfed and the squad formations were already improved. The problem that you describe has already been solved. It seems like you are playing several patches in the past.
I honestly can not agree about indirect fire units in general being OP. Pak Howi and Scott yes, the rest is balanced or even underwhelming.