Foundation Findings - Foundation Repairs- Austin, TX

I hear that 2"-3" is the norm and that no foundation is ever zeroed out? One engineer tells us that it slopes and to have it repaired. The other says there are slight variations but does not suggest any repairs? The slope claiming engineer used a water level. The variation claiming engineer states that a more expensive tool called a zip line level should be used for more accurate measurements? No cracks or sticking windows present. What would you advise to your client?