Here's what I have been advised.
Right to Left languages can't be edited using RH HTML editor.
However, if you use any third party tool for editing HTML files and
you don't open the same in the Design view, you should be able to
produce an Arabic Help.
I am also told it is possible RH for Word might work and that
may handle Right to Left Languages. Note however it is a "might"
work.
I guess that window property would be needed in that case.
Does that help?
Help others by clicking Correct Answer if the question is answered. Found the answer elsewhere? Share it here. "Upvote" is for useful posts.