It is impossible to see the sparks of a tail strike through the window.
Maybe not the sparks themselves, but...beacon flashes are quite easy to see against the ground during takeoff, and if the sparks off my grinder are anything to go by, dragging the bottom of the aeroplane along the runway would light up the surrounding area like (yellow) daylight. Maybe not see the sparks themselves, but the glow from them, you bet you'd see it.