I agree with your point that gH and kH should not be equal. They do different things and they have no relationship with one another besides CaCO3.
I advised searching for Diana's posts more as a bookmark for discussions about water params.
My view on pH is that it's useless on telling what is wrong with your water. The fact it has so much focus puzzles me
Whatever changes you do. Do them slowly as in weeks. I had Staurogyne melt in the span of a few days after bumping my gH considerably. Plants and fish do not tolerate quick changes but they can adapt.
Snails will feed on the remains from your fish. Or broaden the feeding area. When fish are occupied in one part of the tank snails will eat in the other.