Indeed it should. What happens is that I am an idiot
and didn't realise I have to klick the "show-me-how" button to activate the script.
Although I didn't see that in any player's guide.
Just started a new game, and the sack script worked (ie, the VG booted me out of Rome and took it in one turn), but the Eternal city wasn't sacked and abandoned, but made the capital of the Visigothic realm.
Should they do that?
BTW, I think the Visigoths, hell all the horde factions, need a little love. Slaughtering those huge stacks is too easy. Maybe the staple horde units should be beefed up a bit?