Any translation system that doesn't involve humans is AI. Not all translation systems are languague models (those that are not, mostly suck), but AI is a much broader term.
But I don't think there is an issue with using language models for translation if you tell it to "translate close to the original and conserve the tone, style, voice and nuances of the narration as a professional literary translater would". In the publishing industry translations are well established, and we wouldn't debate authorship of a translated work. Even machine translations are now fairly common in professional publishing, so it would feel weird if this site had a higher standard.
Obviously, don't use AI for creative writing---the results are just not good.
Edit: I use gemini pro, most of the time when I need to write in German (often multiple time a day), and most of the time it does a fairly good job.