One question, would the event have made it possible for Cornelius to persuade Acilius on a 2 if I had tried?

Ah, good question! {checking}

Cornelius has a combined Ora+Inf of 8, and Acilius a Loyalty of 7, so with no other factors that would need a total of 1, which is impossible, but the Omen random event would add +1 to your 2d6... ah, right, no, your minimum roll would have been 3. (Snake eyes + 1.)

On the other hand, knight persuasions need >=6, so adding +1 to the roll helps that persuasion. But it doesn't help senator Persuasions, it hurts those chances: you've got to roll

equal to or under <= the target number. (If you add a bribe, you're increasing your target number, not increasing your roll total -- increasing target number gives you more room for success under your target.) And if you roll too high a total you fail anyway, which the +1 makes a little more likely. (This prevents late game players with high cash and influence from instantly succeeding on any senator persuasion attempt against the senators of other players, which would badly unbalance the late game.)

In short: the Evil Omen helps you a little picking up minions, but hurts you a little picking up senators. Proportionately however, it helps you more on knight persuasions (improving your chances by 1/6th) than it hurts you in senator persuasions (reducing your chances by 1:36.)