Perhaps a silly question, but is it possible to have things animating in the background while running a dialog?
The function 'repeatedly_execute (_always)' should keep on running, and any existing animations should keep going as well. Note that Display () blocks all of those, but DisplaySpeech () and DisplayTopbar () do not.
I think the game is paused when a message or when dialog options are being displayed. You can have it run while people are talking but not while dialog options are being displayed.