The Jaguars would absolutely take this one. We’re talking about over 3 Jaguars per man. A jaguar has a bite strength of 1,500 PSI, that’s more than enough to crush a bowling ball and human skull. Add in bloodlust and you’re going to see the Jaguars leaping straight for heads.
Worth mentioning that jaguar’s preferred method of killing is biting through the head. I am unable to find much info on how sturdy the helmets of this period of history were, but presumably steel of good quality. I’m thinking a jaguar couldn’t do much to the helmet, but it certainly can injure the face and throat very significantly.
The Lorica Hamata of the Roman Legionary only covers the torso and groin. That leaves a huge amount of the body open to biting and rending. It’s also important to note that the Roman soldiers, as most anyone would, would absolutely lose it at the sight of 100 giant cats sprinting at them. They’re trained to fight other humans, not take on 3 cats per man on a very open, flat environment. Additionally, jaguars weigh from 100 to 160 kg. If one jumps at you, it’s not going to be easy to deflect or deal with if you find one on top of you while two others are coming for you.
Scutum shield would be semi helpful but very limited. The gladius would likely be far too short to help too much in this situation