Discourse greets users by showing “Welcome back, johndoe!” banner. First of all, I think it’s not very friendly to greet by the user name. I would expect to be greeted by my first name.
But then we have a problem.
Many inflected languages such as Czech, Polish, Ukrainian, Greek, and Hindi have a vocative case used when addressing a person directly. In these languages, the correct form of a name changes depending on grammatical case – for example, in Czech “Petr” becomes “Petře” in the vocative. Supporting name declension (vocative forms) is therefore important for localized greetings.
It would be great if greeting by first name would be supported along with vocative case. I can imagine there would be a user editable field in the user profile, that could be as well processed by AI in order to help find the correct name form.