ETK diagrams aren't usually the best indicator, but you can see it here:
Part #1 is the E46 M3 strut hat. As you can see, the hat itself is eccentric, meaning the center shaft where the strut is installed, and the 3 bolts holding it to the mount, are not equal distance.Therefore when you swap the left hat to the right, you can potentially gain negative camber.
The following is the strut assembly for the MZ4:
The 3 nuts holding the hat, and the center of the shaft is concentric, or equal-distance. Therefore when you swap the hat left to right, it makes zero difference as to camber. As for how your caster got so out of whack, I can't explain that, since the hat is the same PN for left and right on the MZ4.