Stealthed Wild Elf walks into a flashbang... attacks without any problem because he isn't blind. Also, in another game. Deployed Electric Elf Dude triggered 2 flashbangs, no blind and no dmg taken.
Confirmed Stealthed units do not trigger the damage/blind properly. Confirmed that units being deployed do not the damage/blind properly.
I want to add that stealthed unit are also immune to head of osarius fire aura (see it in a game where my DE scout stop in front of it...)