Luc

Why do lucky days come from replies with vowels in them?

Not technically an answer but perhaps the absence is surprising / of interest to someone:

We don’t typically do this in the Netherlands. I find it very strange to call someone something that isn’t their name (or at least a part thereof if the parents chose something unwieldy), especially to the point where a culture develops a set of default secondary names based on their real first name. Mostly obvious ones but sometimes also entirely unguessable. I learned this is a thing in other countries from my German partner

We do have birth names (some biblical crap, like the holy Johannes for someone called Jo) but it’s not like they’d ever introduce themselves to anyone as such (not even when meeting the king). It’s not their name, their parent doesn’t say it when they’ve done something wrong, and I doubt they’d respond to it if it’s not super obvious from other clues that you mean them. It’s just there for ceremonies at church altars and airport terminals

German also has Mustermann (“Muster” meaning template)

We don’t have that in the Netherlands or in English afaik and would use something like Smith, that is Janssen in our case. Of course you could also see something like “Last_name” or “Example” in the place of a last name field, but it doesn’t look like a name the way that yours does

Janssen or Jansen (without that final s) is also the default last name in the Netherlands

In the north you find a lot of de Vries (the… frosty? There’s an origin story involving Napoleon that I don’t know whether it’s correct)

Regarding Peeters, a crush of mine was called Peters, in Dutch Limburg. Besides that I don’t know the name so I’d guess it’s uncommon here