How close must you be to true level to not harm refrigerator

It is leveled to the floor of the freezer compartment (that's what the little bubble that came with your RV is for). You're not trying to level the RV, just the fridge (the two are not the same).

When we first get each new RV, we find a place where the fridge shows as completely level, the we shim a bubble level till it shows as completely level, and glue it down (where the driver can see it). That way we know that the RV is level to the fridge.

We always have used a quarter level as "close enough".