Since the games' save files are stored in "C:/Users/[name]/AppData/Roaming/Renpy" [...]
Are
also stored in. It don't invalidate what you said, but people must remember that it's only one of the two location where the save files are ; the other being the "game/save" folder in the game folder.
It's important because, when deciding what save file will be used, Ren'py compare the date of both file, and use the most recent one.
Lets say that you play the update of a game today, and use the slots 1-1 and 1-2 to save your progression. Then you encounter an error, and ask for a save file that don't have this error. You get one, that use the slots 1-1 and 1-2, like you, but that have been made yesterday... Ren'py will not show them to you if you put them in only one of the two save folders.