Once the UI is created, modifying the UI to be difficult changes need to be done via verbal description of the desired changes. A visual editing tool to adjust size of objects, change fonts / colors would streamline this process. For example, a "whiteboard" like capability where you could graphically revise and refine the UI and then have this consumed by Builder would be a great improvement over having to try to get Builder to make UI refinements via text prompts. This was a point of frustration with several teams that wanted to refine the UI after initial generation by the Builder.