You didn’t mention why you’re trying to bind-mount your /data volume from your initramfs environment, but the only reason I can even guess at is that you’re trying to use it as part of your recovery environment. In which case, you’d probably be better served by doing the recovery from an Ubuntu live usb rather than try to cobble together a working environment from the shrapnel you left scattered across your drive.
This process should literally look like – boot, mount drives, rsync /usr back to root volume, clean up fstab/any other config changes, reboot, try again later after you’ve done more reading.