You could try heating the area, perhaps with a hair drier. Sometimes the clear coat can repair itself and the etching slowly disappears.
Other than that I'd suggest a very mild cutting paste, something like Meg's Ultimate Polish.
I had the exact same units fitted to my CLS to replace the foglamps and give me DRL function. Very good quality units, was the auto-electrician's verdict and must say they performed flawlessly for the 4yrs I had the car