if the scratch not that bad, just live with it...I also badly scratch my moms accord rear bumper on wesak day..... same like u, on the wall. my mom tak tahan looking at it, so send to workshop repaint the rear bumper.
bout the touch up paint, don't waste time n money. i tried b4 using those DPI, the colour came out different even the colour code is the same. wuahahahaha. lucky i just spray it on the eye lid. now i make my eye lid cf style. coz hate looking at the different colour tone.