I think there is something of a false distinction being drawn here, that between formal and dynamic equivalence. The latter, too often, is not dynamic at all. I noticed at Mass yesterday that the phrase "in like manner" had been replaced with "in a similar way." Both phrases mean the same thing, and it is not merely that the new one is flat and banal. It is also condescending. The idea behind the new phrasing is that ordinary people won't understand the earlier phrasing, which is nonsense. Generations of ordinary people made their way through the King James Bible without needing intellectuals full of themselves to translate it into Dick and Jane prose.
I also know of no evidence that Benedict "wishes the Latin Mass had never been replaced by vernacular versions." He was, after all, a peritus at the Second Vatican Council.
What is wrong with “I am not worthy to receive you, but only say the Word and I shall be healed” is that it leaves out the reference to the soul that is the point of the original Latin, which adapts what the centurion said. It is the soul that is being healed, not your bunions.
My own take on the new translation is that it is better, but could be better still. And that the Tridentine original is incomparably better than any vernacular version so far.