I honestly don't think anything with the NPS is straightforward, including complaints. About 10 years ago, my wife was navigating through the marina to our slip and some swimmers jumped off a houseboat in front of her so she had to move over to miss them. Unfortunately, the houseboat across the way had been parked with its tail way out the back of the slip so that they could sun on the top deck. My wife hit their slide with the boat tower, causing it to pop off of the support brackets. She tried to see if there was anyone on the boat but nobody was present. She docked the ski boat, went over to the houseboat and searched everywhere, but no owner to be found. When I got there, we went over to the marina office, reported what had happened, asked them to get us in touch with the boat owner, but they said they would have to act as the intermediary because of privacy concerns. They attempted to notify the NPS and a ranger said they were too busy to look into it.
Two weeks later, we get a call from NPS telling us that they are planning on issuing us a ticket for hitting another boat and leaving the scene. They told us that someone had seen it happen and that we ran off without doing anything. After a long explanation, along with a discussion of our statement at the marina office, it turned out that they were likely relying on our own self report to the marina office. No ticket was issued but they talked to us about the proper way to report an incident. The marina office never did get us in contact with the other boat, but during our discussion, they felt the boat was in the wrong for parking 20 feet beyond the limits of their slip, creating a navigational hazard.
I don't have a lot of faith in rangers doing anything that requires follow up, just the things they witness themselves. There is way too much evidence over the years of limited enforcement going on and non-existent after the fact enforcement.