It will supply way too much magnesium for a given need of calcium. As a magnesium supplement, it supplies way too much alkalinity for raising magnesium levels.
Nothing uses calcium, magnesium, and alkalinity in these ratios, so it doesn't really balance any particular needs in the aquarium.
If it were adequately pure (evidence of which is almost certainly not going to be provided), it might be useful as a little daily supplement in addition to a much larger amount of calcium and alkalinity, so as to help balance the magnesium loses due to calcification. One cannot wait for an apparent need for magnesium, however. It would need to be added very frequently in small amounts (because of the fact it supplies alkalinity as well)
Bear in mind that dosing acetate can potentially cause a depletion of O2 if too much is added at once.