default XCURSORPATH is not xdg spec compliant
As you can see in xcursor.c, the only per-user directories for the icon themes are ~/.icons/ and ~/.cursors/. According to the xdg base directory specification, it should at least also be looking into ~/.local/share/icons/ or $XDG_DATA_HOME/icons/ if $XDG_DATA_HOME is set.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information