Can I paint frosted glass panels?
Removing paint from glass is pretty much always easy. It's hard to scrape it off if the surface is rough and frosted but then again, glass won't be adversely affected by paint removers. If you were to go with film, most of the adhesives that hold them on are pretty serious - always test first. 

For this, I would use lots of thin layers of spray paint. This would make the surface appear smoother since I'm sure there's some texture with the frosting, and the spray paint will stick to the low spots and even up. Make sure to mask it off well!