Hi! Unfortunately, there's no one authenticating Celine here at the moment.
Your best option would be to hire an authenticator for a small fee. Google the services and please read the reviews, because there have been cases of people claiming they are knowledgeable about a brand and charging buyers and sellers money only to make rookie mistakes that had our authenticators here on the forum have major facepalms.
I can't recommend anyone in particular for Celine, though, sorry.