I'm experiencing the same problem. The haptic feedback (in the beginning sometimes, now next to always) create a noticeable clicking sound when I dismiss the control center (by sliding up) and when dismissing reachability (by sliding up). It sounds metallic and off, as if something is loose or broken.
It occurs when the sound is turned on, although I have had a couple occurrences (clicks) using force touch in silent mode.
Like you write, the behavior can also can be reproduced (sometimes - not always) when selecting the vibration pattern S.O.S. or when changing vibration patterns rapidly.
I have sent feedback to Apple and been in touch with Apple Support in Norway. They hadn't heard about the issue. Since some people say that the iOS 11.2.5 Beta has helped, I think our best bet is to wait for the official update and see if it helps. Hopefully it won't be long.