Yup, I think you've about got it. Nicely done. Your off-rhymes remind me a bit of Brodsky, who seems fond of them. Your English reads pretty fluently, except, to my ear, this line - "and there the strong juice reaches, pressing it" - which might have room to be tinkered with, though the German there is a tad awkward as well, it seems to me.
I might say "the Mandorla" instead of "a," since for each holy figure in a mandorla, it's not a random one, it is intimately associated with them. I'm not 100% sure though, I just found "in a Mandorla" a bit random, like "in a Chevy Malibu."