You're using "My Documents" folder. it's special folder(Download, Desktop, etc) of windows.
those special folder has 'windows account name' on absolute path. (ex. "My Documents" = c:\Users\windows username\My Documents\)
if your username has multi-bytes characters, BepInEx occurs error on load. try move game folder to another place. (ex. "d:\games\Spending a Month with My Sister\")
Sorry but your cheats don't work for me in any capacity. My computer's just too weird I guess. It's Win10. I tried moving the entire game folder to my D Drive, nope. Moved to desktop, nada. Moved to C/Program Files, and still no. Nothing I do enables your cheats.
I downloaded and tried both BepInEx for x64 and x86 and both doesn't work. Honestly I also had an issue at the beginning starting this game up trying to get the English translation to work because for whatever reason the files available here for the game? The original download has everything translated into Chinese for SOME REASON.
I guess I'll just have to grind through this game. It's such a stupid grind especially with the damn cat.
The steps I tried to get your cheats to work:
I downloaded both the November and December versions.
Downloaded and put BepInEx in both.
Booted up the game and closed the game.
Put the Cheats into the BepInEx/Plugins folder
Booted the game, tried pressing F2 and F3, nothing happens.