I got my Cornwall 4’s to behave better by making wood angle jigs screwed to the base risers of the speakers and screwed to my wooden floor. These jigs are aligned with the back wall such that measuring their leading edge distances to the back wall allows for them to be precisely angled in tandem from the back wall. Speaker angles are derived by measuring the outside toe-in speaker corners from the back wall, and the speakers are always in exactly the same plane relative to each other.
The jigs also can be slid laterally along the floor (and locked) at minutely varying distances using each jig’s built-in scale without affecting their distance from the back wall.. This allows for them to be precisely centered to my listening position at minutely varying distances while still being in exactly the same plane with each other. So, this allows for the speakers to be kept at precisely the same angle relative to each other and to the wall behind them and the side walls no matter how you move them.
I also made an added 3/4 inch plywood base that is screwed to the underside of the factory risers with a sandwiched layer of that rubber shelf liner sold at Home Depot, etc. This reduces cabinet resonances without over-damping the cabinet.
Cornwall 4’s are notorious for being very finicky about placement, and these measures have made that a non-problem. These tweaks have revealed to me the full potential of the speakers for imaging and soundstage though they are still not "champs" at that.