Monika's answer didn't work for me in MS Word 2019, it does not accept inserting Unicode character in Multilevel List dialog (I tried both Alt+200F and 200F then Alt+X methods).
So I tried adding an space after separator character (the .) in Multilevel List dialog. It fixes the RTL problem, but there will be an empty space between numbers.
Things will get a little tricky if you want to get rid of that space. You need to use a Zero-width space character instead. It's a totally invisible character but behaves like a normal space. Follow these steps:
- In your document type some word (like "سلام")
- Put the cursor in the middle of the word
- From "Insert" tab click on "Symbol" and then click "More Symbols ..."
- In "Symbol" window go to "Special Characters" tab
- Find and select "No-Width Non Break" in the list and click "Insert"
Your first word in document must look like "سل ام" so far. Although letters are right next to each other, but there's something there between them that beaks the word, you need to copy that to the clipboard!
- Use Shift and arrow keys to select that, you won't see anything selected, you just need to feel it
- Press Ctrl+C to copy the character
- Form "Home" tab click on "Multilevel List" and then "Define New Multilevel List ..."
- In "Enter Formatting ..." text box, put cursor after separator character(s) and press Ctrl+V to paste, again, you won't see anything pasted
- Click OK