Career site Builder Backup
To back up Career Site Builder, you can use the export feature available in the Import & Export section. This allows you to export site settings and Career Site Builder configurations into an XML file. You can choose to export the current settings or select from previously saved configurations. Ensure to include the Core CSB Settings option, as this is required for exporting. Additionally, you can opt to export fonts, images, email layouts, and category pages as needed. Store the exported XML file locally for future use or to import into a new site.
How to download the backup files
You have to perform three downloads. One for Settings, one for Career site Builder Settings, and on for Category Pages.

Are custom plug-ins saved in the downloaded file?
No