Our website is available in six different languages. Users have a profile that they can fill with text-based information.
This leads to the following issue: The information given by the user will be in one specific language that will not match at least 5 languages the site supports. But, of course, the profile can be accessed in all languages the site offers. Then all menu items etc. will show in the desired language, but the main content will stay in the language of the creator.
We are using hreflang, of course, which works fine for the content we create ourselves in six languages. But it will fail, of course, with all the ugc content of the profile pages that is only available in the mother tongue of the profile's owner.
How should a webmaster deal with this regarding SEO?