Rear coilover adjustment very different side to side

MaysEffect

They don't adjust ride height, they adjust asb pre-load. In the case of adjustable ride height and corner balancing, the actual lengths between one corner and the opposing may not be equal, as such the length of the endlink needs to be modified accordingly to zero out preload on the sway bar. Having a endlink with a fixed length limits your ability to reduce asb preload in the situations where you have to adjust ride height.

As much as 5mm of height indifference corner to corner is enough to make a significant amount of preload on the sway bar. on average you can have up to 10mm of height difference depending on the driver weight. This is enough to put a lot of bind in the axle and start cause worn out endlinks and subsequent "noises". It will also impact steering linearity and weight jacking through a corner depending on which side is preloaded more.