Temporary jailbreak of iPhone 4 for purposes of deleting a dictionary I need to temporarily jailbreak my iPhone 4 to fix Apple's iOS 6 bug making it impossible to access Japanese-to-English dictionary.

All I need and want to do is delete Japanese-to-Japanese dictionary.

Is it possible to tethered jailbreak iPhone 4 temporarily, delete the relevant folder, and merrily continue using the device in a non-jailbroken fashion?
Unjailbreaking a device without restoring it is currently impossible.

If you don't mind using a jailbroken device until it's fixed, you could jailbreak normally, then when Apple releases the fix, just backup with iTunes, restore to the latest iOS, and then restore the backup.