Formal:
* Welkom terug: This is the most common and straightforward translation.
* Van harte welkom terug: This is a more emphatic and friendly version, literally meaning "Warmly welcome back."
Informal:
* Welkom terug, hé! This is a very informal way of saying "Welcome back!" using the common Flemish interjection "hé."
* Fijn dat je er weer bent! This means "Nice that you're back!" and is a friendly way to greet someone.
* Leuk dat je terug bent! This means "Great that you're back!" and is also a very friendly and informal greeting.
Other options:
* Welkom thuis: This translates to "Welcome home" and can be used if someone is returning after a trip or absence.
Ultimately, the best way to say "welcome back" in Flemish depends on your relationship with the person you are addressing and the context of the situation.