Simply reduce its range, so it has to be played with more risc. With its hp and armor advantage it should be played like that.
Like Panzerwerfer can only clean team-weapons if it goes to the magic < 60 range mark, but is a one-shot.
That would be 50 range for Cali, way too less. But 70-100 seem to be fair as max. range.
Making it more like an assault howitzer e.g. Sturmtiger.
This idea gets a solid no from me, dawg.
Unless you plan to add bonus damage vs vehicles, what with it being more akin to the sturmtiger