It's a good guide to the Romans. I think the early Principes are spearmen, so a bonus against cavalry should be added to their list of advantages. Conversely, I guess a possible disdvantage of the late Principes is that they now lack spears. But in EB, I'm not sure you'd want to charge Principes with cavalry.

On the accensi, I think they are rather good against javelin-armed skirmishers (they out-range them) and also decent against cavalry. There may be a difference between their historical status (described as "poor") and their in-game utility (I love em).

The levees benefit from a large unit size. It makes them surprisingly robust - they can take a beating and still be useful. They are very handy against phalanxes (can't be caught and can maneouvre round the flanks); less required against barbarians. Like the accensi, they are vulnerable to cavalry (can't skirmish move out of trouble quickly enough to avoid the charge).

Is there really a difference in mobility between hastati and principes? I've not noticed one. That hastati just seem inferior to principes due to the lesser armour. They are cheaper, but arguably not enough to matter. If they do have a faster speed, then that might give them a slightly different role.

You probably want to stress the difference between the early and late triarii. The former is a phalanx unit, with all that entails. The latter is just a spearmen unit. The phalanx is rather slow for the Roman battle tactics, but good against elite infantry (e.g. pinning gestatae). Unless flanked, most non-phalanx infantry just can't hurt them. By contrast, I find them too slow to be much use against cavalry (they can't catch them). By contrast, spearmen's raison d'etre is to fight cavalry. (They probably have a hardcoded disadvantage vs swords). Apparently early triarii will be nerfed, but right now they are gods.