I would have just taken the headlights out so you wouldn't have to mask and less chance of damaging the paint. Just 4 screws.

Should have practice on some old junky headlights.

Before

https://scontent-b-ord.xx.fbcdn.net/...81096173_n.jpg

After

https://scontent-b-ord.xx.fbcdn.net/...06250500_n.jpg

Per the picture of your headlight, you have not sanded all of the clear coat off yet. All the clear coat needs to be removed before progressing to the finer sandpaper. I increased the amount of sanding time as I progressed to a finer paper.

Facelifted headlights, you have to remove the bumper to remove the lights.

I agree on pre-facelift lights, it's easier to just remove the headlights and not have to worry about the paint.