Sometimes the file name has the developers name instead of the package name. Maybe look for that?
Edit: Oh yea, also, sometimes there's not a plist in that caches folder but instead there will be an actual folder. Then inside that folder you'll see a few db cache files for the package you're trying to clean up. I usually delete the tweak folder inside that var>mobile>library>caches directory. For example, Barrel creates a folder called aaronash.barrel.settings or something like that. Since I removed barrel and no longer use it, I deleted this folder for the above directory.
Hope this helps. Let me know if you have any questions.
Edit: Don't forget to empty the trash can if using iFile and you have that feature turned on in its settings.