- Test yourself, how the FileExporter and FileImporter looks with an RTL interface, and correct the errors you find (or create tickets for them if they are super big)
- Test with one of your colleagues who know RTL languages, if anything looks fishy to them
Where to test
Go to https://test.wikimedia.beta.wmflabs.org/wiki/Special:ImportFile and add any URL from a "real commons image" like the picture of the day.
(Note: Neither the URL-input page will be available once this is deployed, nor will you be able to actually import images from Commons. Both of this is just test set up)