Should this implicate that Luhmann invented Noteboxes? Because this is absolute not the case. There are many famous Zettelkaesten from famous people. The most famous might be the Mundaneum, a kind of wikipedia in noteboxes, from around 1900.
What Luhmann did was adding basic hypertext-principles to a common note-taking-tool.
That word isn't in general use in German, and it's certainly not in general use in English. So I don't see any confusion.
No, it is not. The term was already around decades before Luhmanns birth.
> That word isn't in general use in German
Despite the fact that the https://en.wikipedia.org/wiki/Leitner_system was pushed by just about every teacher.
The usual word is "Karteikasten", "(Lern-)Kartei" oder "Vokabelbox".
How is your own lack of knowledge relevant for this?
Did you even bother to at least visit https://de.wikipedia.org/wiki/Zettelkasten to educate yourself first?
> The usual word is "Karteikasten",
That is a modern synonym, but not quite the same. This is more specific for organized indexboxes.
> "(Lern-)Kartei" oder "Vokabelbox".
Those are not even the same. They are special purpose-tools with specific meaning which just happen to use index-cards and boxes in their analog version. That's like saying notebook is not a word because diary is widely used.