To get a very shallow, but noticeable, engrave in PG acrylic, I used speed:800, power:65, LPI: 270, and defocus:0.25. I believe 270LPI corresponds to SD. The defocus (0.125 above the nominal surface) helps to smooth out any artifacts from the mastering.
I created a mini material test board that only varied power and speed in a grid of rounded rectangles and chose what I liked the best.
Note that I only changed the acrylic engrave because the default deep etch did not suit my taste. But, it would be perfectly acceptable to leave the engrave at the default setting. The only tailoring needed is for the engrave on the draft board to create enough room for the LED.