Proposed resolution:

Change the returns clause in [facet.ctype.char.members] paragraph 10 from:

    Returns: do_widen(low, high, to).

to:

    Returns: do_widen(c) or do_widen(low, high, to), respectively.

Change the returns clause in [facet.ctype.char.members] paragraph 11 from:

    Returns: do_narrow(low, high, to).

to:

    Returns: do_narrow(c) or do_narrow(low, high, to), respectively.