Once iOS files are backed up to iCloud, can you access them programmatically?
Apple's iCloud programming guide states:


  Apps that use iCloud must be signed with iCloud-specific entitlements. These entitlements provide a level of security for your app by ensuring that only your apps can access the documents they create. 


So I don't think it's possible to retrieve another app's data without compromising the application's private key, which should be safely stored on the application developer's computer. (And backups, hopefully)