If I print this on clear plastic (Acetate) do they show through with the button lights on OK or should I go with just plain white paper ?
Acetate (i.e. overhead projector slide media) is OK, but there is no adhesive backing so the inserts can rotate under the cap.
IMHO white paper looks awful because of the fibers revealed by the backlight.
Consider using Avery 8665 or 18665 (inkjet)
or Avery 15665 (laser) full-page, clear, adhesive labels
or clear waterslide decals instead.
Scott