org mode table alignment issue with CJK characters

[Zelphir Kaltstahl <zelphirkaltstahl@posteo.de>]

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Hello org mode users!

I recently looked into getting org mode tables to properly align cell borders 
and table border, when using Chinese characters in them.

I found out, that there is valign mode [1] and was happy with it for a few days. 
But then I opened a document with lots of tables and some of those tables bigger 
than what I had before in other documents. Scrolling inside that document became 
quite laggy. So teeth-gnashingly I deactivated valign mode, already suspecting 
it to be the culprit. And I was right. After deactivating it, I could scroll 
perfectly fine again.

So I returned to the second alternative I had found out about, when searching 
for a solution: Finding a font, which renders Chinese characters at exactly 
double the width of latin/ASCII characters. I found a font named "Sarasa" [2] 
and experimented a bit with setting the font globally, then setting it only when 
opening an org mode buffer. Now it looks like that font does character widths 
almost correctly (see attached screenshot, see slightly wider 4 ASCII characters 
than 2 Chinese characters).

My settings for org mode regarding fonts/faces are:

~~~~
(add-hook 'org-mode-hook
           (function
            (lambda ()
              ;; Only do the following in graphical mode, as it will
              ;; break when using emacs in terminal mode.
              (when (display-graphic-p)
                ;; Sarasa font is fromhttps://github.com/be5invis/Sarasa-Gothic.
                (setq buffer-face-mode-face
                      '(:family "Sarasa Mono CL"
                        :weight normal
                        :height 110))
                (buffer-face-mode)))))
~~~~

However, it seems, that now org mode does not align tables correctly, even 
though an ASCII character is half the width of a Chinese character in the 
tables. Org mode seems to add too few or too many spaces, which are displayed as 
spaces of various width.—Is that because of the 1 pixel width difference?

Do I need to look for another font, which does things truly exactly, no 1 pixel 
too wide funny business? Maybe someone knows a more exact font?

Ultimately: How can I make tables align correctly?

My Emacs version is: GNU Emacs 28.2

My org mode version is: 9.6.1

[1]: https://github.com/casouri/valign

[2]: https://github.com/be5invis/Sarasa-Gothic

-- 
repositories:https://notabug.org/ZelphirKaltstahl

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