You will not be able to have access to the information of the guests that have canceled. All of the personal details get removed as soon as cancellation takes place. I used to copy down the phone number of each guests once they booked. I did it because I’ve read reports here that host get canceled here without reason and no longer have information about future staying guests.
How were you thinking of contacting them? All airbnb has is name and phone number. Perhaps keeping a guest book is a good idea going forward or asking them to feel something out before they leave - like a suggestion card but ask for the info you want as well