Ok, I've just pushed a new version
of the "Open format externally" plugin which should better handle foreign language titles and also multiple entries in the sub-menu for the same format. So for instance if you have multiple EPUB editors or applications you can configure them as individual menu items.
In addition I have added support for command line arguments if the application you are launching needs them. So you can think of this plugin now as a fairly generic application launcher for a book format that should hopefully have flexibility for most situations.
To support these changes I have changed the structure of the configured tweak menu inserting two new columns. So the few people who jumped right on the very first version today should re-read the new tweak text in the post or readme.txt in the latest zip.