Acetone will break down the acrylic, but since its only at the surface it should be a series of scratches and small craters. I have used acetone to break down the tear away paper from really old panels of acrylic only to do some surface damage. It will polish out using something like Novus, but depending on the damage it may take a while to sand out. Unless there was an existing subsurface crack, acetone in cleaning amounts shouldn't do anything major to the material integrity.
