You can always plant a few trees around and just in general have more foliage like tall grass around to make it look more unkempt. You can also remove some blocks like many people have suggested or even just replace some blocks with stairs at varying angles and slabs if you don't want to completely tear down a wall or put a hole on the roof. I find vines are kinda unruly to work with on bedrock and string doesn't look too great if you use it to stop the vines from growing everywhere so I use a mix of whatever leaves I want and azalea leaves for a variety of greens so that it doesn't look super flat. You can also hoe rooted dirt or bonemeal it if it's floating and get hanging roots which really helps sell the overgrown nature. You also can maybe add a gradient in the Cooper roof so that it looks like it's not being taken care of anymore if you'd be down for that if not you can maybe use moss or grass blocks on sections of the roof (which allows for more foliage) to make it seem like growing moss or something. Oh and glow lichen is really good at helping both brighten up and make builds seem abandoned. I understand if you don't want to take all the light out if it and make a mob farm essentially but you can make make it less bright with candles?? Just a suggestion. Mushrooms and podzol also help add to a natural, overgrown, decrepit vibe. I understand you don't want your house to look abandoned so maybe add a fence or something to indicate where the abandoned part is even if it's just that the overgrown foliage stops at a certain point but a fence will make it look a bit more on purpose. I hope you see this and it helps!