This seems to imply the second translation is better because it flows more naturally than the first. It's true, and the first is a bit awkward. But the second translation misses a lot of the art of Livy in this passage; for example, the highlight of Hannibal's speech is equating the Alps to the walls of Rome (the Alps are the "walls" of Italy, and his army is going to cross the walls of Rome just like it crossed the Alps), by using only one word (moenia: walls) for both, whereas the second translation flattens this completely by dividing it in two words (threshold and walls). The first one was bad too by using a vague "boundaries" for both, but at least kept the equivalence.
Livy was more striking and elegant than both those translations, and yes, the goal of a translation should be to accurately convert the choices made by the latin writer. It requires art and craft, sure. (But note that I gave the passage to Claude and it correctly used "walls" for both...)
Here's a bit of Livy we were translating the other day, which do you think is better and which is more accurate to the author's language?
(AUC 21.35)... Hannibal in promunturio quodam, unde longe ac late prospectus erat, consistere iussis militibus Italiam ostentat subiectosque Alpinis montibus Circumpadanos campos, moeniaque eos tum transcendere non Italiae modo sed etiam urbis Romanae
Hannibal, the soldiers having been ordered to stop on a certain promontory, whence the view was long and wide, shows Italy and the fields around the Padus placed beneath the Alpine mountains, saying that then they were going to cross over the boundaries not only of Italy but even of the Roman city.
Hannibal ordered his soldiers to come to a halt at a certain lookout, from where they could see far and wide, and pointed out the land of Italy to them, and fields around the river Po set at the feet of the Alps, declaring that soon they would cross not only the threshold of Italy but even the very walls of the city of Rome.