It won't do any of those things because you'll have to compensate for this by using that much more up elevator trim which will cancel out the bad stabilizer trim. The model will fly as per normal.

Depending on how much negative incidence the stab had to the wing on the plans having 1 or 1 1/2 less negative isn't neccessarily a bad thing. But if the stab is actually at +1 to 1 1/2 compared to the WING's angle, so the stab has more positive angle than the wing, then I strongly recomend that you cut into the model and correct the issue. A stab that is more +'ve than the wing will require a bucket load of up elevator trim and won't look very nice.