Is your issue with the single coil not matching..? Cause at that point they are also not hex bolts.
I would say just ignore it. I know that isn't a great answer but there really isn't much to be done.
I have however in the past taken a dark silver nail polish and coated screws on a guitar to change them from black to Cosmo.
Maybe able to do something like that.
I did the same thing to my invaders cause they had black poles. I carefully backed them out, put them in a drill and spun them against 0000 steel wool till the black polished off and made a Cosmo chrome. Then sealed them in a super thin coat of the dark silver nail polish and buffed with compound.
The only screws I didn't do where the night adjustment screws for the pickup.
Every other piece of metal is Cosmo on this guitar.
It was Alot easier to start with black screw and make it Cosmo, you would be starting with chrome.
But any bit of color on a silver metal goes a long way.
Who knows, maybe even sealing the top may even protect it from rust longer lol.