So, people are going to have their opinions on AI, and of course, you are using it regardless, so I don't necessarily think it becomes more or less considered "scummy" to base it on a particular art style. I think it would be best to pick a good style, which I think you already have with whoever you're basing the style on, and just keep the art consistent. The only real alternative is to commission or hire an artist, but that depends if you will be making money from this project or are willing to sink a lot of money into said artist.
There are plenty of Visual Novel Games on Itch.io that use generic AI images for their games, but I like that you mostly have a consistent style and would think it best to keep that visual identity.