We have installed a plugin to allow for inline translation of forum posts, utilizing the Microsoft Translation API.
To use the translation function just click the icon at the bottom of a post. This will translate the post into your Interface Language (details below on changing this).
This helps us read conversations in foreign languages, but doesn’t do as much to help us respond to them.
If you run across a plugin to allow translating replies from English into another language (this would be the language used in the thread), then that could be helpful too.