As with Lorca's other poetry, the Spanish of "Sleepwalker's Ballad" is deceptively simple. With my poor Spanish, I can more or less read the original without trouble. However, this ease of vocabulary masks the complexity of his poetry and his untranslatable word plays.
Take the lines "Ella sigue en su baranda, / verde came, pelo verde, / soñando en la mar amarga." This translates as "She is still on her balcony, / green flesh, green hair, / dreaming of the bitter sea." The line is good. The poetry is good in English. But an untranslatable play of great beauty has failed to make the trip into English. In the translation, the sea has the quality of bitterness. But in "mar amarga," the word bitter contains the entire ocean - amarga. The possibility of this line does not exists in English.
In The Poetics of Translation, Willis Barnstone asserts that translating poetry is fundamentally impossible and that, for this reason, it must be attempted. The green girl is still on her balcony. The sleepwalker still aspires toward her, bleeding. We see them more clearly with every flawed and lovely failed translation.