I am tempted to copy out a verse or two of Chamber Music to illustrate my point about poetry being a very hard thing to translate, but my lawyers have advised against doing this.
You do find the word 'air' being used a lot. This has a double meaning. Mostly, Joyce uses this to mean 'tune', 'melody', but the other, more common meaning colours this. There is a lot of air in these poems. There are other words that reccur over and over.
What suffers in translation? The double-meanings? The rhyme scheme? Everything, perhaps.
I have read a lot of Dostoevsky and Gogol in translation, with absolutely no hope of ever reading it in its original Russian, but reading more than one translation of the same work, you can see just how much actually changes, and there there is no rhyme for the translator to deal with, although every writer has their own particular rhythm, especially Joyce.
My first introduction to the work of James Joyce was listening to one of the albums by former Pink Floyd genius/madman Syd Barrett who set 'Golden Hair' to music. In his own lyrics, anyone with a familiarity with Joyce will hear the influence in Barrett's work, particularly post-Floyd.
I think I'm going to Dublin for a Joyce pilgrimage!
You'll have to visit Paris, Zurich and Trieste too. Oh! The hardship!