iPhone Contact Reverts to Old Data After Edit
Hmmm... In general when I run into syncing problems like this I'll log in on icloud.com with my Mac to see what's in the cloud (versus what my devices show).

For problematic devices it's recommended to remove the account (or just disable Contacts from iCloud in this case). When prompted, choose to delete the local data. After a few minutes enable it again and then be patient everything syncs.