Jin,
Thanks for adding your signature.
The clicking noises are usually (if not always) attributed to structural adjustments of soft tissue post-operatively. Not sure if that would include facet joints (Z joint) or not. But in regard to your question, I don't think I've ever read a post from a patient (since 2004) that decisively stated that the clicking was from a poorly placed ADR.
Yes, complications have occurred; I am only addressing one of your specific questions.