Shame about the mishap with the decal. It was coming along really nice.
Maybe Tamiya is able to replace the decals. Try to contact them directly or through Rainbow Ten, a store in Japan.
I would definately NOT apply any clear over the wax. Most likely they will react or the clear will "eat" the wax.
Many waxes come out with some dish-washing soap. Give it a try on a scrape body.
Good luck,
Lusitano