@KyBunnies: Three things must happen for CC to update an is_read column in calibre.
The first thing you must do is create the correct column(s) in calibre. Next you must tell CC what calibre column is to be used for is_read. See our FAQ answer
Can I synchronize CC's Read and Date Read information with calibre?.
After you have set up the columns then when you finish reading a book you must change the is-read indicator in CC. You do this in CC's Book Details for the book. Once you change it here it will be synced back to calibre the next time you connect as a wireless device.