If you are referring to the ,dat and cache folders within the C:\Program Files\MAGIX\Photostory Deluxe\ version subfolder - do not touch these.
The files you can delete safely are the .H0 and .HDP temporary files that are created in the same folder as any video clips, I would recommend only doing this when you have completed and exported/created a slideshow from a project - if you ever have to reload and modify the project at a later date these files will be recreated.
Other locations that can be deleted depend on Backup requirements and future planning for returning to a completed project to re-edit it etc.
If you are using the Backup copy, Copy project and media to a folder for 'archiving' a project then the AudioTemp folder can be cleared of files.
If you have to go back to a 'finished' project, at a later date, that has been backed up you would copy the backup to a working folder edit etc and back it up again when completed.
If you do not back up the project and you empty the AudioTemp folder, then on reloading you will be asked to locate the missing audio files.