The step where it says H2SO4 over the arrow, there is also water. And the side product is 2 CH3OH.
The H2SO4 step is acetal hydrolysis. Two of them in a row. There needs to be water. It is almost roughly assumed that H2SO4 contains some water. It doesn't
Also I'm not sure why you are saying enol tautomerization. I'm not seeing any tautomerizations, although I didn't write it out in detail so there's a possibility I am missing something.