This is the general problem with literature and poetry especially. They're not entirely translatable.
- Languages are part of culture and they are historically conditioned, making them necessarily bounded and finite [0]. While the essential thing signified may be the same for corresponding words in two languages (snow vs. Schnee), there is variance in semantic emphasis, connotation, and symbolic significance. In other words, the pragmatic aspect of language is highly contextual and conditioned.
- Words can be used univocally, equivocally, or analogically, and there isn't necessarily a correspondence between these constellations across any two languages. But so much of wordplay trades on such constellations.
- The syntactic and phonetic features peculiar to a language - apart from the what is signified per se - is heavily exploited by poetry.
[0] This reminds me of words like the Greek λόγος (logos), which does not find a satisfactory counterpart in any language as far as I can tell. (Approximations are Tao, Ṛta, or Ma'at, for instance.) You see this difficulty in the translation of John 1 where it is usually rendered verbum or word, which have their own perfections, but fail to do justice to the richness of the original meaning of Logos in passages like John 1:1 and 1:3: "In the beginning was the Word, and the Word was with God, and the Word was God. [...] All things were made through him, and without him was not any thing made that was made." When you substitute "Word" with "Logos", you can clearly see how much more pregnant that message is, e.g., that, contrary to the pagan mythology of those John was addressing, in the beginning there was order, not chaos; that God is Reason; that everything that exists is caused by God and therefore fundamentally intelligible. (Curiously, the Latin Verbum is better than the Greek at emphasizing the procession of divine Reason as Second Person from the First Person in the Trinity.)