Has anyone tried different Coil Overs other than the KW ones? Like Volvo or Mondeo ones,

 

From what I understand jaguar took the rear suspension off of the mondeo wagon, while the front is a mondeo sedan. The suspension was of course modified to accommodate jaguar's needs. So I don't know how the fitment would be honestly, I've only done very limited research so take my knowledge lightly.

However I know you can use the rear upper camber from an 2003 volvo s40 (as well as any other year or model that shares the design). It's a direct fit and can be used for better alignments or camber correction when using lowering springs. I understand this may not be info you are directly looking for, but may serve useful to you at some point.

Hopefully this will help you out! Best of luck in any further research you do