Isn’t it possible to use 3PO to deliver the line in a way he would say “The Republic won’t send reenforcement/ships/fleet ? We are doomed !” ? (note that Daniels made 3PO voice in TCW, I wwonder if someone familiar enough with the show would know if there is a line to be taken from an episode)
Since he doesn’t have a mouth to sync to the line this would be the simplest solution. It should be possible to piece something together from all the voice work he’s done for TV, games etc.