Two device handy box (683)
I'm kind of confused as to why the box does not have a plaster ring on the box. Generally we used to retap to an 8/32 since the 6/32 is stirpped I don't think you would be able to retap. Probably wouldn't hurt to try. You can order trim screws with painted heads but you would probably have to order from an electrical wholesaler or a specialist like Fastenal and you probably would have to order a bulk amount. Last ditch if you can find a #8 or #10 metal screw with a trim painted head we have used them from time to time. I would cut off the point before installing so it wouldn't puncture the insulation of any wire.