Translating poetry is not the same as translating any other mode of text - it requires not just converting a body of literature from one language to another, but necessarily rewriting parts of it to fit with the metre, rhythm or other nuances in the original that are vital for reproducing the original reading/recital experience.
The Danish poet and translator Holger Scheibel (b. 1936 -) wrote in the postscript to his 2022 translation of Shakespeare's sonnets, that his translation was not as much a translation as a Danification inspired by the original poems - one that preserved the form and meter of the sonnets so as to not sacrifice Shakespeare's own personal expression.
In other words:
It must therefore be assumed that the chosen form and its meter before and during the writing had a played a crucial, indeed, excluding role: Precisely this is how the poem ought to look and nothing different. We can from this deduce that the form must remain unchanged, that when it comes to reproducing the poem in another language? Yes, it is certainly that assumption that is the basis for this treatment of Shakespeare's poems. The strophic form is an integrated part of the poet and the poem's linguistic expression.
(Scheibel, Shakespeare's Sonetter, pp. 162 - 163; Translation is mine)
Scheibel himself had also personally translated the lyrics of every one of the Danish composer Carl Nielsen's compositions into English, as part of Carl Nielsen Udgaven ("the Carl Nielsen Edition"), of which can be legally viewed online for free.
As a translator you must also have a modicum of experience or knowledge of the genre or work that you are translating, as such having just the basis of knowing about poetry means that you are able to replicate if imperfectly the nuances of the source text into the target language to give the readers a taste of the original.
It is essentially to be dishonest towards the original poem's author and your audience. I am not saying that you can translate it into prose - if to aid students or laypeople in understanding the literal meaning of the original poem, but it sacrifices the spirit of the poem and utterly destroys its body for the exchange of getting an ungainly retelling of its details. Robbing it of its melody, wording and basically spirit.
Literary scholars and translators such as professor J. R. R. Tolkien and Robert Alter have both in their various essays and prefaces noted that translation of poetry, is the translation of something carefully made and cannot be rendered into any other form - without losing some aspect of it.
Translating poetry from one related language to another is one matter altogether, taking then a poem and translating it from a language from one wholly unrelated language family to the other, where such tropes or poetic devices are non-existent requires some igenuity on the translator's behalf.
This is where we come to the main subject of the essay, taking a look at Japanese translations of poetry with very specific forms that require a more attentive focus on these aspects to properly convey to the readership how the original may have sounded.
The Rime of the Ancient Marinere
The naval epic by Samuel Taylor-Coleridge from 1798, The Rime of the Ancyent Marinere, is written in the style of a shanty, giving it a folksy rhythm, but suiting its character of an old marinere relating the horrors that he witnessed whilst aboard a doomed ship.
More technically, according to a scholar:
The poem is written in iambic meter, the first and third lines of each regular stanza containing four, and the second and fourth, three feet. The regular stanza form has four lines, rhyming abcb.
That is, it's written in the signature style of Shakespeare and his compeers, but written in a time hundreds of years after the Bard's death and in a very archaic style, conciously evoking an ancient language fit for its narrator and protagonist.
(...)