Jacey is a modern creation. Sometimes it does come from the initials J.C.; the parents of the gymnast Jaycie Phelps are named Jack and Cheryl, and they created her name by combining their own initials. The name has probably also been independently created by many parents simply by creating a rhyming form for names like Stacy and Tracy that starts with the now more popular Jay- syllable.
Kimora is probably an African-American creation, because Kimora Lee Simmons' mother is Japanese, and according to people I have consulted who are experts on the Japanese language, Kimora doesn't have any obvious Japanese meanings. So Kimora is best thought of as a blend of the sounds of names like Kim and Ora.