Lots of people from all over the world have joined Vivaldi Social :tony_wee:, which means you'll come across posts in many different languages. We have 2 tips for you:
1. Go to Preferences > Other > Filter languages to select in which languages you want to see posts in.
2. When posting, select your post's language (from the same menu as attachments, content warnings, etc.), so the right people won't miss your posts. You can set a default language in Preferences > Other > Posting language.
@Vivaldi It's also possible to follow a profile only for posts in a certain language. Click on the Profile -> Three dots (...) -> Change subscribed languages. It's available on servers running 4.x, can't speak for 3.5.x.