I don't understand.

You do a manually chroot, so you go to the installed version, and after you call mhwd-chroot.
If you have only one installed system, it can't do again a chroot ?
From the live, install mhwd-chroot and use it directly ?
You absolutely don't need all those mounts...

mhwd-chroot is done to replace them.
(edit)
You can't do a chroot from the installed version to the live, because the live is not installed.