Is there a translation copyright?

Question

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It has always been interesting what the legal relationship of copyright to translations is. Everything on the web is very blurry and incomprehensible. Maybe on the toaster, who knows.
Task:
to publish translations from English into Russian and from Russian into English for their projects (70/30).
Copyright indicate:

• necessarily
  
• desirable
  
• doesn't matter (it's completely legal anyway)
  
• doesn't matter (it's completely illegal anyway)
  

Which of these is the correct answer?
On Habré and on other resources I see an active link to the translation. But on habré, as I remember, it appeared there due to the fact that not everyone immediately understood that this was a translation (and the link itself used to be at the bottom of the article)
It is clear that no one will sue me in the international court because of the article, but here more interesting is the legality of translations (on the one hand, this is a unique text, but on the other hand, it is the use of someone else's copyright for free) and whether it will be enough to indicate an inactive link to the source.