> ...
  > could only come from texinfo.tex.  Is that where you saw \rawbackslash
  > etc.?  If not, where did you see them?

Yes in texinfo.tex, in the definition of @t{} (L2836).

Another idea is that maybe texinfo somehow doesn't recognize “ and ”
and uses ASCII approximations?

  > I changed that to @kbd already, so I guess we should leave that for
  > now, and wait for complaints.

I agree.

  > ... If you can show that the PDF which is produced by that is
  > incorrect, then we could try other methods...

More pictures, all of them are from Emacs manual for 26.2 (that's six
not five).

Pictures from chapter PDF4.1 & INFO7.1 Inserting Text: 'p1', 'p2'.

Pictures from chapter PDF11.19 & INFO14.19 How Text Is Displayed: 'p3'.

Pictures from chapter PDF22.5 & INFO25.5 Quotation Marks: see 'pic2'
from previous e-mail and 'p4', 'p5', 'p6'.

  > That's not how I recollect this.  I think we originally did use @samp,
  > but moved to @t in the case of quotes because @samp gave sub-optimal
  > or even incorrect results.

Ok, but @samp{} shows grave accent ` and apostrophe ' correctly, while
@t{} makes them curved.

  > I see nothing wrong with pic2, that's just how PDF renders "straight
  > apostrophes".  So I see no reason to move away from @t in this case.
  > ...
  > I don't understand what problems you see in the shape, the text as
  > typeset looks OK to me.

See picture 'npic2' (= pic2 + zoom in), clearly:

A. quotes on first /like this/ are curved, they must be straight,
otherwise "... typewriter convention, which quotes using straight
apostrophes..." will make no sense, because we will show incorrect
form.

B. `..' and ``..'' (second in npic2) also must be in typewriter shape
because we want to show how curved quote convention looks like, so
they are part of example and not part of main text (see picture 'p0'
for example of quote that is part of main text).


  >> But if you really want to go with how Unicode docs do it, then:
  >> U+201D @sc{right double quotation mark}
  >
  > OK, done.

Cool, except you need to correct Unicode code for right single
quotation mark form U+2018 to U+2019 (Quotation Marks chapter -
footnote).

  > I rearranged the words there to indicate that there other bindings
  > of 'undo'.

Thanks.