Interestingly, all 4 revealed battles and mine are from the same generation, all within about a 20 year period. Considering that Roman history spanned 1000 yrs this seems potentially significant. But I wouldn't call it a theme split because Badger is in that list and (I think) TUF is not. If I'm wrong about TUF it could be that all these battles belong to one generation of Romans although there's only a couple of really famous one's left- Pharsalus, Philippi. If Wylted's Mt Vesuvius is legit, tho, then there's plenty of less famous battle to choose from.
3 Roman civil wars and one Roman disaster. If the scum's theme is Roman disasters then Cannae and Teutoburg Forest are even more famous distasters than Carrhae. Catalaunian Plains was a less famous disaster, although Rome lost two Emperors in battle there.
It seems unlikely to have Ancient Roman battles without including Punic War (several gens before the battles listed here)-
Cannae is one of the top 5 most famous battles of all time
Teutoburg forest and Zama are also quite legendary
Pharsalus was more decisive than any of these.