There are many ways to make Havarti. In most methods, you drain off a lot of whey... something like 50-70%, or all of it, and then add it back in the form of water. If you remove that much, and add water, it will change the calcium and pH makeup. with gouda, the drain target is less, more like 30-35%, so the goal is lactose removal, although it also washes the curd. There's this continuum in terms of how much the curds are washed and how much calcium you remove.
Sorry for the confusion... there are many approaches to it. I was trying to make a distinction between various ways to wash curds in water to point out that is leads to different levels of calcium loss.