Re: group slugs when i18n environment
From a quick Google search it appears that, yes, WordPress slug titles need to be improved to support i18n efforts. All the WordPress slugs – including the BuddyPress group threads – go through sanitize_title().
A patch for sanitize_title() to support i18n slug names for the WordPress core is the way to go. I don’t understand what’s required as I do not know much about i18n, so I’m leaving this alone.