What motivates decisions in the translation process?

"No one will ever read you as closely as your translator does." —George Szirtes
The "translation" of text (poetry, novels, short stories and so on) is unique in that the only hindrance is language. Taking a novel and turning it into a film is called an adaptation, and the film is not expected to be digested in the exact same spirit, because they are different mediums and multiple new components are at work. For example, to perform an original song as it was intended is arguably not a creative endeavor, but a display of skill. Therefore, a song is often performed in a different style to emote a different feeling (which is called a cover).
Translations, however, are a unique brand of artistry. They are often expected to show prowess in both linguistics and creative writing. They are tasked with mimicking the substance, emotional pacing, impact, stress, and slang of the original text through their own language and interpretive lens, which forever makes the translation imperfect from the beginning.
Anyone who has ever tried to learn a language will find that there are often no direct translations. The strength of the original word in its original context and original language will inevitably lose the punch that was intended when translated, but it's the translator's job to get as close as possible without sacrificing the visceral components that come about when reading the text. (Poetry is even more difficult when syllabic and syntactical properties are to be taken into account.)
The following are two different english translations from the same line of text:
“A strange melancholy pervades me to which I hesitate to give the grave and beautiful name of sadness”
“This strange new feeling of mine, obsessing me by its sweet languor, is such that I am reluctant to dignify it with the fine, solemn name of ‘sadness’ ”
They both may fundamentally say the same thing, but they may not "feel" the same way. When it comes to art, how a line feels is very important.
https://www.theguardian.com/books/2016/jul/24/subtle-art-of-translating-foreign-fiction-ferrante-knausgaard