[villagetinker]

You could try calling home warranty for information on the 'tile' and the installer. Then call the installer to see if they have matching bull nose tile, and have this cut to fit and properly attached and grouted. Now if that is not an option, I would go to Sherwin-Williams and ask an expert what type of paint to use and the s[pecific preparations so the paint will stick and wear will. I am guessing the are where the material was glued will need to be completely cleaned, and probably sanded, and maybe sealed or primed before the final coats are applied.
My other thought would be to use a contrasting or highlight color tile if you cannot match, and then the correct method to attch the tile.