It should be fairly obvious that using Akeeba Backup for Joomla! to backup and restore a site made with WordPress will not work very well. Joomla! and WordPress are completely different. As a result they need a different restoration script to be included in the backup archive at backup time.
If you want to be able to back up and restore your WordPress site you need to use Akeeba Backup for WordPress. There is a free Core version which you can try. If you decide you need the Professional one you can buy a BACKUPWP subscription. Since you're already a JOOMLADELUXE subscriber our system will give you an automatic 40% discount off its price.
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!