I don’t speak Swedish, so I am relying on machine translation here, which admittedly may be causing issues. However, the machine translated version of that Lawline article looks fairly clear. They are using the a word that most literally translates as “plagiarism”, but it carries a meaning that is very clearly closer to copyright infringement.

Kind of like how French “demander” might literally be translated into English as “to demand”, but its actual meaning is closer to English “ask”. Related, but carrying importantly different connotations.

That’s not me staying confidently that you’re wrong about Sweden having plagiarism laws, but only that that source does not (if the machine translation is to be believed) prove the point you thought it did.

A good rule of thumb to tell if a law is actually about plagiarism per se (and not copyright infringement) is to ask whether it could apply if you were doing it to Beethoven or Shakespeare. Or even to yourself, because “self-plagiarism” is a thing—you need to cite yourself if you’re referencing something you yourself did previously —but “self–copyright infringement” is not.

Another feature of plagiarism is that it is entirely alleviated by clearly citing the source. If you can say “this part of my text came from this source” and avoid the fine, that fine really was plagiarism. If not, it’s probably copyright infringement.

argumentations in the swedish judicial system are not written in the impenetrable formal language of anglophone countries and are actually quite simple to parse, since they are not being used as precedence (since sweden is a civil law country rather than common law).

This is fascinating. Personally I’m not a lawyer, just an amateur with a passing interest in the law. I’ve read a handful of judgments and tend to find them fairly easy to read. Legislation itself can be impenetrable, and references to it can make a judgement difficult to follow (as can references to precedents), but assuming you know the black-letter law, I think most lay people can read a judgement and follow its logic pretty comfortably, even in common law jurisdictions.

But that is still definitely a fascinating hypothesis. It kinda makes me wish I still frequented Reddit, because it reminds me of conversations I’ve seen and even participated in on /r/auslaw about different legal systems (an interesting one: why America’s encoded civil rights in the constitution directly help lead to the activist judicial system they see today, which itself is key to Trump’s rising fascism, compared to another common law country where the constitution only lays out more basic, mundane things like how the number of Senators is calculated). I would love to see what more lawyers familiar with either system think about that point you make. It’s a very intriguing one.