Unzip the backup directory and open entities.xml.
Go to the attachments directory and open any directory. The directory name is a page id. Each of the files in the directory is an attachment that must be renamed
Rename to what?????
Search entities.xml for attachment objects with that page id. When one is found, locate the attachment id and filename.
How use .xml editor???
Rename the file with that attachment id to the original filename and test it.
How to test?
Find the next attachment id and rename it. Repeat for each file in the directory.
Once all files in the current directory are renamed to their original filenames, search entities.xml for the page id, eg directory name. Find the page object with that page id and locate its page title.
Rename the directory to the page title and move on to the next directory. Repeat for each un-renamed directory in the attachments directory.
To import each file back into Confluence, upload to the original page by attaching the file from within Confluence.