Proposed resolution:

Change "3.9.1 Additions to <cwchar> synopsis" to:

       namespace std {
       namespace decimal {
         // 3.9.2 wcstod functions:
         decimal32  wcstod32  (const char wchar_t * nptr, char wchar_t ** endptr);
         decimal64  wcstod64  (const char wchar_t * nptr, char wchar_t ** endptr);
         decimal128 wcstod128 (const char wchar_t * nptr, char wchar_t ** endptr);
       }
       }

Daniel writes:

- 3.9.1 'Additions to <cwchar>' provides wrong signatures to the wcstod32, wcstod64, and wcstod128 functions ([the parameters have type pointer-to-] char instead of wchar_t).