Are my data backed up, and can a backup restore something I deleted?

Backups are used to recover the service after a failure. They are not a way to undo account deletion.

Deleting your account removes your diary, profile and chat from the live service. Calsa sends deletion requests to its processors that day, and the backup copies expire within 35 days. Payment records are kept for seven years and for at least one year after the subscription ends. A payment attempt confirmed as unsuccessful, with no charge, is kept for 13 months after that final result. Restoring the service must not make a deleted account available again.

Download and check your export before confirming deletion if you want to keep a copy.