I hadn't seen entr before! My first glance at your one-liner:
find $ORG_DIR | entr -r rclone sync -v $ORG_DIR $REMOTE:org
is that find will enumerate all your existing files, but starting a new one won't get picked up.
It seems like entr is prepared though, and you should just pass in -d. In fact why use find at all, if you want to rsync the directory?
I didn't know about entr as well but I'm using fswatch which is largely similar and portable as well, supporting not only Linux and BSD but also non-WSL Windows and Solaris too, and leveraging the Filesystem Event API on macOS.