First; is “Folder” really the new “Directory”? I never know which to write these days.
Second; don’t set up an FTP server and and then use the file system to change the name of a users home directory. The FTP server won’t know about the name change. Maybe it should. Maybe the file system should have secret hidden random names for things that an FTP server can use to access the folders and files. If you rename something, it doesn’t matter because that’s just the visible name.
Just a thought.