Apple has provided the FBI with decrypted copies of the iCloud backups. But the phone only backed up "intermittently" so recent activity would not have been included in those backups. (Well, it COULD have been, except that the FBI told San Bernadino County to change the password, which messed that up.)

iCloud encrypts backups at rest but it's not encrypted with a key that only the user has, it's encrypted with Apple's key.

They probably have, but the whole point is they want a way to decrypt the device, to use as a precedent in future cases.