If you got the vents out, you're a better man than I...
How's pin stripe tape look?
The trick with masking tape and Plastidip spray is scoring the desired paint margin before removing the masking tape, or the tape brings the Plastidip with it. Tape would eliminate this issue, and would likely be an easier way to black out the other bright spots. I used a black paint pen on the vent flap controls, and directional tab, applied after the picture. I'd love a better way...
There is a release tab. It's hard to find, but once you find it the removal is easy. I'll need to have a new look to refresh my memory. If that works, I'll post a tip.
The black tape was not really glossy, but it was not "flat;" so, it is not a 100% solution. It was effective enough that I never notice the reflection unless I'm looking for it.
I think that the best solution would be to buy the 2015 vent as a replacement. I understand that it has no chrome, but is all black.