This is a very interesting essay on “The Poet as Translator”, which quotes a lot of good translations, some in full. The writer’s own translations are included elsewhere on the site, and are worth reading.
The essay is very big on getting into the same emotional state as the original writer, or at least thinking you are. I think there’s a lot of truth to this. Since there’s no way of knowing exactly what was felt and meant, you may as well throw yourself into your interpretation wholeheartedly. As with singing, nervousness is no help. Better to be boldly off-key than shakily true.
On the other hand, there’s really no way to feel what someone else is feeling without engaging your brain. And the process of writing itself is a curiously unemotional thing; you and your feelings are no more present in the flow of making than you would be thinking about the rights and wrongs of nations or the details of your buddies’ lives in the middle of combat. You are too busy doing to feel or think. You are too busy making words say what you mean (what you feel) to actually feel them. The only use of emotion in poetry is to bring you into a state of making poetry. Emotion comes back afterward, but it’s shoved aside during.