Stabilize metal legs attached to wood table top
Sometimes, attaching the X-frame legs so that the back plates are closer together than the front plates will allow the front legs to act as stabilizers vs sideward movement.  This solution assumes that the plates are not rocking; that the screws threads are gripping tightly and the screw heads don't permit any rocking of the plate, either (ie. use of washers keep plate firmly against underside of table).