I'm using EasyDiscuss in a multilingual install of Joomla with SEO enabled. The URL's always reflect one language (oddly, it's Spanish, which isn't even the default language on the site).
In any case, the language code in the URL is correct, so it it generates 404 errors anytime a link is clicked within the EasyDiscuss platform when that link is clicked from a language other than Spanish.
Example:
The tag links here:
http://turningtechnologies.com.br/en/help-and-support/tags
have a path of:
http://turningtechnologies.com.br/en/ayuda-soporte/etiquetas/tags/turningpoint
which is the correct language code (en), but the Spanish version of the path instead of the English version.