As for current Vermin Swarm army book entry names, sheesh, it's a slim army book that was made to give people something to play, with entry names almost certainly decided on before much if any fluff existed. Furthermore, it's not meant to be a fantasy clone of ancient Rome populated by ratmen. There is Avras, a fantasy clone of ancient Rome populated by humans in the T9A timeline, one that was suddenly overrun, usurped and appropriated by ratmen. Whether the Vermin Avrasian Republic actually continued business as usual under new management or mainly just appropriated its identity, symbols and outer trappings isn't quite clear. In the present era though, it's gone way more towards the latter it seems, as their domination over Fantasy Europe has been broken. I'd say the current Vermin Swarm is about as similar to Human Avras as the Carolignian Empire was to the Roman Empire, or something like that is what I hope the background team has in mind.
If the skaven are nothing to you if they aren't mad scientists whose weapons work in wildly random ways, then I suppose T9A isn't for you. T9A cannot simultaneously be everyone's ideal of what they would want Warhammer to have been, because ideals vary between players more than most realize. T9A tries to cater to a broad audience, which comes at the cost of being less perfect for someone with very narrow, specific preferences.
I don't think there's anything bland about Vermin as they are in T9A. Strength in Numbers is still there, which creates a number of interesting dynamics. They are the only army to get massed cheap numbers with independent Ld 8. That means they get cheap numbers for swarming and grinding, *and* the staying power to stick around and do so even when not supported by characters. The downside is that that staying power is conditional on deep ranks, and that if they do flee, they aren't likely to rally anytime soon, both which rule out MSU tactics, requiring them to instead play as relatively inflexible battlelines and be vulnerable to enemy force concentration.
All which supports a playstyle of bringing a mountain of models onto the table, something that is very much consistent with Vermin fluff. A good rule design is one where fluffy armies actually work.