At the match Rick is giving Kai instructions, which makes no sense. He's not her trainer and not even undercover as her trainer. She doesn't even really know him.
The Kumu story line with the skull is factually inaccurate. It is illegal for anyone to own the remains of a native American, which includes native Hawaiians. There are many laws on the books meant to protect the cultural heritage of indigenous peoples. In addition, the repatriation of native relics has been practiced for decades. It would have been more accurate for Kumu to have involved the Justice Department or other legal aid which would have helped to repatriate the skull rather than commit "grand larceny."