Most paint will flake off eventually from glass. Glass should really have etch or etching paint applied so the paint can grab a non-smooth surface. A clear (translucent paint) over top a frosted (or sanded) clear (paint or glass) will be unfrosted after. The final finish of gloss/flat is decided by the topcoat.
Cleaning the glass real well will help adhesion, and usually baking the paint with heat before full cure helps too. (power it while soft, but after any heavy flashoff of carrier which may be flamable)
I've used testors enamel translucents with good results too.
Ive painted lots of bulbs and no paint caught fire, even if it discolored and flaked off fast . Still, wet paint and dry paint "flame on" differently, be careful.
