I think the impact is even better with the crowd reacting to “The day of victory is at hand”, like they realize there’s an evil scheme that’s approaching soon, which Poe comes to explain afterwards with “He’s been planning his revenge, his followers have been building something for years…” etc.
And like I said the extra line makes it feel more like they’ve been hearing to a longer message, since “the great error is corrected” doesn’t sound like the beginning of a phrase, now it feels like we hear the final words of a longer speech. The speech ends with Palpatine promising their victory approaches = the crowd gasps.
The extra line also gives more breathing room for the audience to understand what’s going on in the scene (a large crowd hearing to a recording of Palpatine), a first time viewer will probably “get it” after the establishing shot & the first line, alongside the gasps of the crowd. Where as the current version feels a bit “blink and you’ll miss it”.
^^^^