The biggest thing that prevents this edit from working for me is the “It’s the First Order, they’ve done it” moment. Not just Finn’s dialogue but the music. It’s the tragic violin Starkiller Base music, where I think exciting action ramp-up music would now be more appropriate.
Some time ago I played around with that scene as well and I used “Kylo Ren Arrives at the Battle” from the awards consideration score for the music. First the part from approximately 0:15 to 0:27 for Finns solo scene and then 0:45 to 0:55 for the rest of the scene. Keep in mind that the album version of this track is different!
And for Finn’s line I suggest to wait for the upcoming movies. Maybe John Boyega says something like “They’re here.” or “They found us.” at some point so that this line can be used here.
But I think “They’ve done it.” works fine actually.