I was thinking the same thing. Its not the sprinkler that was being controlled, but the sprinkler system. Also, I feel like the team was really focused on how the machines worked, like, did they see/hear/think etc. You have to remember though that this was before everyone automatically assumed a living machine being is an AI. This was back in the Poltergeist days. Historically, a living machine/object was thought to be a ghosts or spirit or witchcraft. In this case it happens to be (maybe, kinda?) aliens (or maybe Comet Tail spirit). If you replaced aliens with ghosts, it would make a lot more sense as to what it is being controlled and why it is behaving the way it is.