If you put clear tape on frosted glass it becomes see-through. You could try that if it's meant to be a momentary peek-though situation.
Or you could mostly frost it with white alcohol ink. Just leaving enough of an open lattice to achieve a veiled appearance.
I'd think a decent way to accomplish that would be to put on some gloves, wad up a small piece of fabric, wet it with the alcohol ink, then dab it on the glass. Practice on a scrap piece of clear plastic a few times to get the technique down, like from a 2-liter bottle that you cut apart.
I remember hearing about see-through concrete that had similar properties: link to article
