Hello,
If you have some issues with restoring a backup, please contact me to my support e-mail.
Currently the backup file contains all settings except the thumbnails (images).
The cloud contains these data as well and when you login on a new PC, it should download it automatically.
There is also a History feature that can help when you lost your local settings (this can happen if you downgrade from Firefox 63 to any previous version).

Best regards,
Juraj Mäsiar