In article <5268d87d0912141704k5eb7ae24p777096a93cbbc0d2@mail.gmail.com>, Christian Wittern <cwittern@gmail.com> writes:

> I just confirmed with the released version 23.1 that this problem is
> still existing.  It is very disappointing and keeps all Mac users I
> know from upgrading to the otherwise wonderful release 23.  Is there
> anything I can do to help getting this issue fixed?

Emacs supports unicode-sip displaying at least on Unix/Linux
where we can use fontconfig and freetype.  See the attached
image (result of M-x list-charset-chars RET unicode-sip
RET).  Emacs asks a font-backend to get a font whose
registry is "unicode-sip", and fontconfig backend searches
for fonts that support at least U+20000 for such a request.

Perhaps, Mac's font-backend is not doing that.