How do I mod in the unadded equips?
If you have a recent version of the game, there should be a folder called "Mod" in the game's directory. Just insert the pictures there. In the example posted above, there are 3 mods for Potion Maker included. The blonde and short haired version are currently in extra folders (inactive), so you would have to copy your preferred version directly into the mod folder (no sub folder), thereby overwriting the Mohawk haircut.
The mod folder is very useful for laymen to change the game, because all you have to do is decrypt the Game.rgss3a file using RPG Maker decrypter, and then start photoshopping the pictures. The easiest mod is arguably removing clothing (simply removing a clothing part from an outfit or removing the entire outfit altogether, then save the empty .PNG.) It's not so useful for Kohaku because you can change her outfit in-game anyway, but it's useful for characters with less clothing equipment options. For example, you can make Potion Maker go nopan. Fits her personality better anyway because why wear panties when you're foreign to the concept of shame anyway?
And with some beginner photoshop skills, you can also edit clothes slightly but effectively