Despite looking similar, air launchers were not Zamor sphere launchers; the Matoran of Mahri Nui didn't have access to that technology.
Solidified air bubbles were used as weapons against sea creatures, to whom air was toxic.
Getting hit by a solidified air bubble wasn't much of a sensation. The sensation was when it turned to air and choked the being it struck.
Hydruka had natural solidified air launchers.
Solidified air bubbles weren't automatically lethal to water breathers because the air didn't cling to them, it just forced the target to retreat.