At the same time, it's almost impossible for us, your fellow players, to give sound advice as you probably can't tell us enough for us to work with. But you can tell staff all of it. The full picture as you see it. And they probably see things you don't so in this you are simply providing them with a more complete picture. There is a good chance they will thank you for the concern and information then handle it as they see fit on their end.
While there are rare exceptions, I generally believe that staff wants to help make the game as healthy as possible. Most in my experience are more interested in helping players than punishing or winning or the like. Of course, sometimes the rules need to be enforced but in most cases I have seen staff try and understand and teach. So I rarely ever feel any reason not to share my concerns with them and I want to help my fellow players and helping staff help them is honestly the best I can do.
Just my thoughts on the matter! You know what's going on and we don't so you are best placed to decide how to approach it. Only think I have left to day is, don't be scared of staff!
Some things may seem unthemely but when you peel layers back, things start making sense. There are times when people do act in ways that are unthemely though and staff will like to try to poke at those things where possible (sometimes its just kind of not possible to fix it entirely). They may not be able to tell you how to handle it or verify certain actions because they'll want to protect that ic ooc divide, but they might be up for a chat.
Hope you sort it!