> For our case, we can install the patched hyphen.cfg under luatex
    > specific path, e.g. tex/luatex/babel/hyphen.cfg. So other engines won't
    > see it meaning less risk for melting the precious latex freeze.

    This would be a good solution, but it's doubtful that the CTAN
    maintainers would allow such a file in their network

Like CTAN, TL already has numerous hyphen.cfg's, so I see no impossible
barrier on that front.  I agree with Robin's suggestion of "disguising"
it as a .dtx.

Of course, Will's original point about the so-far-insuperable barriers
to updating babel remains.