acoustic advice resonating wall panels

The sound pressure peaks force the panels to vibrate, the very thing that the panels are intended to tame. If you take an empty box sealed on all sides except one side and place it anywhere in the room where there's a sound pressure peak or reflected acoustic wave - while playing a test tone circa 300-400 Hz - the box will vibrate strongly. That's why you need to throw everything but the kitchen sink at the sound pressure peaks. Tiny bowl resonators, diffusers, absorbers, Helmholtz resonators, whatever, since the peaks cover a wide range of frequencies. And the peaks occur in the 3D space of the room as well as room boundaries. So the problem is severe.