Calcium and magnesium availability is reduced at lower pH's rather than increased, while micronutrient availability is increased as the pH decreases. Coffee grounds vary in their pH but aren't necessarily significantly acidic, or even acidic at all.
I've used vinegar at the rate of 1 teaspoon to 1 litre of water to correct micronutrient deficiencies but it does have to be repeated regularly, whereas sulphur lasts longer. The vinegar used as a herbicide is stronger. Do be careful with Borax because boron is toxic to plants in higher amounts - it can be used as a herbicide to kill "creeping Charlie" aka "ground ivy" which is one of the plants susceptible to boron toxicity. Boron, being a micronutrient, becomes more available at lower pH's (the micronutrient that is an exception to this is molybdenum).
FWIW, not all sulfates have an effect on pH, for example Epsom salts (magnesium sulfate) doesn't.
Edited to add, pH 7 is neutral - there's a chart showing nutrient availability as affected by soil pH in Figure 1 on this page from U of Vermont
http://www.uvm.edu/~fruit/?Pag...
