Essentially none of the low-flush toilets use all of the water in the tank...the height is there for pressure just like a from a water tower - height=pressure.
Now, if they didn't choose a properly calibrated fill valve, it might refill the tank before the bowl is full. The only way to tell if the bowl is getting enough water to refill, is to take a bucket and slowly add water. It will only go so high, as the excess will just flow down the drain. But, if you add it too fast, it will 'flush', and you won't get a good indication. If the fill valve isn't balanced, a call to American Standard may be worthwhile, but they'll probably brush this off as 'normal'. The only way to fix it is with a properly designed system, and they aren't the best at that.