update: nvm somebody already made it

I know it's been literal months but man, I'm sad I didn't recognise this and respond to this. Feel free to ask around if you wanna figure out making something like this. Here's some short tips though:
You can't just copy files over with the same name as the base game, you need to point to them in a custom sounds.xml file for some reason.
Don't edit items.xml to change the name and description of Dad's Note, you're better off using a simple lua script like I did to change the one name without affecting stuff like item charges or quality or all that stuff.
Replacing the sprite for Dad's Note is as simple as having the file be the same name in the same locaition, there's no wacky extra steps for that one.