The "Saved Games" folder is one of the Special Folders in Windows:  https://en.wikipedia.org/wiki/Special_folder.
It's default location is %USERPROFILE%\Saved Games, but it can be changed by the user: https://www.windowscentral.com/how-move-default-user-folders-new-drive-windows-10.
I assume in your case that the Special Folder "Saved Games" is located in C:\Saved Games. And SF2NA creates the mod folder there.
Unfortunately all other SF2 games (SF2 Europe, SF2 Vietnam, ...) seem to use an incorrect implementation of how to retrieve the location of the Saved Games folder. They always use the default location %USERPROFILE%\Saved Games.