> If you mean support for changes introduced in Unicode 6.3, then Emacs
   > supports that since v25.1.  But again, what does that have to do with
   > keyboard layouts?

Well as I said keyman software provides (not sure about the license)
free keyboard layouts for different platforms including iOS. 

So in order to have my favorite phonetic hebrew layout for keyman, I
need to modify certain files, (like for example
/usr/share/X11/xkb/symbols/il as  in unix based systems) 
and submit these as patch. 

These modified files need that specific UTF8 support I mentioned and
that is why the keyman maintainers proposed to use visual editor.

However I prefer GNU emacs, if I can.
Thanks to your information I can. 

Did I explain the issue now detailed enough?