Hi !
Sorry for resurrecting this old post, but I had the same question and I was wondering if the *best* current implementation might be home_url(bbp_get_root_slug()); to link from anywhere in a wordpress multi lingual site.
I also looked at the implementation of the breadcrumbs, as they include a link to the root of the forum, but it looked like the implementation only worked when the user is inside one of the forum pages (maybe it has a dependency to a global object?).
Thanks!
