I kinda get that. You want others to play your game, the way you designed it. But you shouldn't limit people from making their choices. Some will play the game the way you designed it. Some will play it by making use of the console. Some will use a cheat mod. Its all their choice, let them make it. You give your best like you do, on making the story more and more entertaining, the game fun to play. That's all you can do, the rest is up to the players.
Well, I am nobody to tell you anything, its your choice too, switching to Unity or staying with Renpy. There are talented people who can even make cheats/mods for Unity also, so it wouldn't make much of a difference.
Although,I do have a question for you. Are you unable to figure out a way to make old saves work? Its always the same issue, that's why I am asking you.