The English language has an enormous vocabulary which allows exact translations to be achieved. That is why it is the language of Commerce. Contracts are written precisely. English means what it says and says what it means. French is the language of Diplomats for the reason that a word can be interpreted in more than one way depending on the rest of the sentence. All papers written in the United Nations for example, are written in English AND in French.
Translations of a given text may vary slightly depending on the translator, but the good translations carry the rhythm, feeling, and meaning of what is written.
it is not a new poem simply because the language is different. One must be, however, fluent in the language in order to recognize an excellent translation.
Un soir fait de rose et de bleu mystique...........
One evening made of rose and a mystic blue.........
Identical meaning, identical feeling, identical visual therefore the same poem.
You would fail translating Jimi Hendrix or Jim Morrison poetry to the same song...words and meaning and it has to rhyme.