When you "add" the lines to the immediate window did you press "enter" to execute the code?
The steps enumerated in the tips page work. I just confirmed it twice.
I think you are getting close. Your OS shouldn't matter. Perhaps the page is a bit confusing because "no" you do not need any VBA to achieve your result.
All you need is:
1. A right to left language enabled.
2. A right to left section direction setting.
I don't know what else to tell you. If you find a way to send me the document I will try to look at it for you. I can't provide direct contact information in this forum.
No joy there. Did you see the feedback link on the web page for line numbering?
By no joy I mean that without seeing your actual Word document then there isn't anything else that I can do for you. The rules of this service prohibit me from providing you a direct means of communicating with me. Silly? Yes, but rules are rules.