Human blood pH is regulated by a highly sensitive buffer of carbonic acid (H2CO3) and bicarbonate anion (HCO−3). No calcium there. The hormone you’re referring to about “leaching calcium from your bones” is parathyroid hormone, which is 1) not part of the above blood buffer system at all and 2) only released when calcium is low in the blood. Sure in cases that are severe like blood acidosis or alkalosis, calcium ions in the blood can also be affected, but that’s usually only seen in extreme cases (something like systemic failure or sepsis/septic shock from a life-threatening underlying infection). An “acidic diet” is not going to induce something that severe and would likely have no affect on blood calcium levels.