Just popping out of no where to dump some of my (might I say) rich Roman knowledge.
#1 - Just because something is named in the latin language, that doesn't mean it is latin or Roman in make or origin.
#2 - The Gladius Hispaniensis was certainly manufactored in and around Rome. What exactly lead the Romans to developing this weapon? It wasn't something that was suddenly created or invented one day. Like all things ancient, it was a slow development from past and present technologies. 1st of all, the Romans did have heavy Greek/ Greco-Etruscan influences since they developed into a city. So why wasn't this weapon developed by the Romans during this time, if it was based on Greek weapons? The Romans heavy Greek influence was rapidly being replaced by heavy Celtic influence into the 4th and 3rd C BCE. These Celts used swords between 60 and 80 cm's, which is awfully close to the size of the Gladius Hispaniensis, don't you think? They even shared an extremely similar blade shape and hilt structure, much closer to anything Greek (Xiphos was the closest, but that blade had a much narrower blade, not close to the Gladius Hispaniensis). The Celts where renowned smiths, and revolutionised many smithing techniques, so it would make sense that the Romans would copy from them, right? We also have the Iberians, which had a very minor influence or placement into the Roman military before the mid 3rd C BCE. There weapons where the closest to what the Gladius Hispaniensis developed into how we commonly see it, and Iberian warriors fought in tighter formations than the Celts, so they needed cut-and-thrust swords that where easier to handle in these formations. So when and why was this weapon developed? Scipio Africanus was said to have re-drilled and trained his army along new lines, incorporating stricter discipline and advanced maneuver tactics, which where based on that of his enemy and his own knowledge. To me, this sounds like a time that Rome would begin fighting in tighter formations, where the cut and thrust sword was a necessity. So the Romans would have began relying on these Iberian swords a great deal more, but perhaps the demand was too high, or blacksmiths back in Rome found this as a good opportunity to mass produce weapons for the army and make some money. Hence the creation of the Gladius Hispaniensis, a Roman sword said to have been strongly influenced from Iberia.
That's my view
I just want people to know that there is never a right answer when it comes to topics like this, but there is always a more plausible one
Just because you read something in a book, that doesn't make it right. What you have read is obviously someone's opinion, and should be treated as such.
EDIT: By the way, I have done a great deal of research into the early Republican Roman Army (between the periods of the 2nd Samnite War and prior to the 2nd Punic War), and I must admit that I am a mega wizz on the subject, and am now one of those educated speculators
Not sure if it's too late now, but I wish to offer help where ever I can.