I tried this out on a completely fresh install as it was broken otherwise. Deleted everything related to Summertime Saga including the \Roaming\Renpy\summertimesaga folder. While the unlocker "worked" it only gave access to 4 characters and not their full galleries except Jenny possibly. When starting a new game with nothing else installed, I couldn't select New or Recap, just Cheat, so not sure if that affects it. Loading the save works, but doesn't give any further access to the Cookie Jar.
Oh, now looking at the unlocker file, those are the only characters the file affects. Did the Cookie Jar for all the other characters just get removed from the game? Did the game restart?