Hello,
there is an old problem with table alignment. It's mentioned here:
https://emacs.stackexchange.com/q/30495/11498

It occurs as far as I know only in 4 cases (last 4 rows):

| 2 latin letters                                 | ab | (2 glyphs)            |
| 2 arabic letters                                | من | ok (2 glyphs)         |
| same but with 2 diacritics                      | مِنْ | also ok  (2 glyphs)   |
| the arabich letter ا and then ل isn't a problem | ال | also ok (2 glyphs)    |
| but ل and then ا is a problem (case1)           | لا | not ok (it's 1 glyph) |
| also ل and then أ (case2)                       | لأ | " (it's 1 glyph)      |
| also ل and then إ (case3)                       | لإ | " (it's 1 glyph)      |
| also ل and then آ (case4)                       | لآ | " (it's 1 glyph)      |

(screenshot)

In the 4 cases two letters build one single glyph and this isn't recognized. That's the problem.
I don't know if it's hard to solve but I've noticed for example that orgmode handles the word  مَنْ correctly. It has only 2 glyphs even though this word has 4 characters (2 diacritics+ 2 regular letters). The alignment is correct (3rd row).
And unfortunately the 4 mentioned cases occurs very often in Arabic, so the alignment would be much worse with than in the example.
I hope this could be solved. Many thanks for the great orgmode features and the bidi support.

(Of course I'm using a monospaced font for Arabic. And the problem occurs also if I only use Arabic letters.)

Kind Regards
Frank