I think it is impossible to translate poetry perfectly.  The rhyme scheme is obviously altered (if applicable) when translated into another language, forcing the translator to use their own interpretations and words- thus altering the original author's intent and artistic genius.  It's almost a new poem altogether.  Additionally, one would have to be a native speaker of the language in order to even attempt to get the full meaning behind certain words and phrases, be they colloquialisms, puns, or literary allusions to other writings in that language.  They may be idiosyncratic to only the people who have lived in a country or countries that both speak that language or have experienced a political or econimic situation which the author has experienced.  So many different variables come into play when one considers "literature"or "poetry" in a language, that it is quite obvious that it is impossible to convey the same meanings in another language without a great many footnotes or notes of explanation in the margins.  Even with these, I feel that the instant-reaction a native speaker would experience while reading would be lost to someone reading the translation.