I wonder if is possible to have an in-game mod for the walkthrough, so far the only engine that i have this kind of mod is for renpy.
Of course you can.
But it will take large amounts of coding.
I would advice something much simpler.
Like a save game just before a particular scene.
In particular those unique scenes like the threesome on the beach with the sleeping mask. You make a savegame file just for that scene. They are not heavy files.
And you replace them, reload the same (no need to reload the game).
Start the project if you feel like it. Ask for help. List the scenes, list the way to reach them. And then make the files. Maybe add a cheat editor (there is one already) and list the settings to change to get different results. Rough score and tan/tattoos configuration.
That's what I would do.
The other way would be a review program using the resources of the game. And that's a whole program. Tons of work.