I do find it strange that the renders are a head of the script as I would of thought it would of been the other way round
Well, someone else has already pointed a possible practical problem, but you also have to see what DarkBlue means with "script". There a few games that start already with a broad script (not really a film script, but at least a kind of trace and mental storyboard), but most have only a broad idea about the story and some characters, that then develop as they go, and I think for DarkBlue that is partially the case.
At one extreme, I know of someone trying to make a game for which had an idea about the character, than started creating pictures with the kind of situations he could imagine, and by when he asked someone else to help glue the story into a game, he had already made 15GB of picture.
Additionally, when writing about script, he may be thinking as "ren'py script", which means effectively programming.
It is true that in the most basic form (a pure VN with no choices) a lot of a game in ren'py is basically the text of the dialogue and the instructionts to show the images, but in general, there is also some "scripting", i.e. programming, and that can be tricky when the game starts to have a certain lenght and size, to do it and make sure everything continue to work properly.
