Unless you set the autobackups to save 'Course backup area' AND to include a specified area AND purposely put the path to the moodledata/temp/backup/ directory am afraid they won't be there in say 4 days. A temp directory is usually just that ... temporary and will be cleaned out sooner or later. Actually, if it's working correctly, one might see the .mbz files there for a little while until the system copies the .mbz to the designated directory. Once it has done that, it is removed.
Your replacing of those hashnamed files with small any K size files doesn't match the meta data concerning backups in the tables of the Moodle DB. While you have been successful in reducing the space, you still have a problem should you ever need to restore a backup. Your only alternative ... a site backup and restore - which is way too much to get a little thing back into a course and might prove to be difficult to do on a remotely hosted system.
No offense ... but much more tinkering like this, Curt, and one should expect a total meltdown. And no one will be able to help.
'spirit of sharing', Ken