The short answer is, Edge Animate doesn't support rtl text.
To get this to work, you'll have to edit the files created output from Muse after doing File > Export as HTML. As part of the output there will be a folder in the assets folder that contains a folder for each of your Edge animations. You'll need to open the .html and add the direction property.
There may be a better way to do this. You might try posting in the Edge Animate forum <Edge Animate CC>.