Very easy to paint out the rivets with touch up paint from Chipex: (you'll need some anyway). I made some dummy rivets when I changed over to the 'proper' catches:

They matched the paint runs on the other body rivets perfectly!
I fitted engine turned stainless steel panels which avoids the colour mismatch, although not good QC to have such a mismatch in the first place.
I stuff the driving mat well out of the way anyway: I prefer to be able to slide my heel of the sheet metal.
Tim