Hi - thank you so much for this useful resource! <3
I noticed in the example script that sprites are cleared manually whenever there is a scene change because of how the parallax effect works. If you try to use the normal Ren'Py "scene," it will not work as expected and character sprites will not go away without manually hiding each one - which is kind of an inconvenience.
In case anyone else wants to use this in a longer project, you can use the python equivalent for "scene" like this with the back layer specified, so all character sprites are automatically cleared when you want to show a new background:
$ renpy.scene(layer="back")
$ renpy.show("bg club")
These two lines together are equivalent to how scene normally works in Ren'Py (e.g. 'scene bg club'), but clears the 'back' layer instead of the master layer (where character sprites go by default w/o parallax).