I have been struggling with what I though may have been a bug in the Frustum calculation in CSM. Turns out lightMargin was the key.
I have some larger scaled objects (trees, walls etc.) and the CSM frustums were not working well for my situation. All I had to do was increase the value (from default 200) to 1000 and now everything looks perfect!
I wonder if there is a performance penalty for having the larger bounding box permitted per-object by increasing this value.
Does anyone know more about this?