I pronounce it seal-ya. I think I slightly prefer
Delia but
Celia is nice as well. I like your ideas of
Celia Rose and
Celia Josephine
Please rate my "Names I would Use" list & "Backup Favorites" list. Feel free to rate some of my other lists too if you have the time.
https://www.behindthename.com/pnl/223226/138473