Legal Question in Civil Litigation in California

First off, you can't sue a Nevada resident appointed under a Nevada court, in California. California has no jurisdiction over someone who lives in another state engaged in activities in that state by the order of the courts of that other state.

Second, unless Nevada law is radically different from California law on this issue (which is rarely the case) you can't sue the coordinator at all. Their court appointment would give them the protections of judicial immunity just like a Judicial Referee or Special Master. The only real chance you would have of suing them and not having the case thrown out would be if the court removed them for actual malfeasance involving some kind of fraud or actual malice, such as if they took a bribe to rule for the other parent.