I learned long ago to clean the screened / printed side of a glass dial
only as a last result

Some of them can be safely cleaned. If you look carefully at the printed
side, on the very edge there may be something like a tiny part number or a
border, not visible from the front. If you are able to clean that without
damage, you can clean the rest of the dial with the same method.

Even if the markings are water soluble, you can gently clean around them
with a dry Q-tip..

Phil Nelson