Hello international users :)
I've made some good progress on setting post languages and filtering.
First, you can set some language preferences in your user manage page:
Second, you can set a group's default language when creating it:
Third, you can set the language of your post when writing it:
If you are not logged in, the home page will be in the language which your browser is set to. If you are logged in, you will see posts in the languages you set on your manage page.
At this time, language filters are not applied to groups, and automatic google translate is not yet implemented.