Michoko I wrote wrappers around Phaser game objects to let them behave like Starling display objects. They are also in the repo.
So, when you convert as3 Sprite you'll get HTML5 Sprite which extends Phaser.GameObjects.Container
It allows adding and removing children, swapping them, looping through them, defining bounds, etc
When you convert as3 Image you'll get StarlingImage which extends Phaser.GameObjects.Image. You can change its texture (by giving an object { atlas: string; frame: string | number; })
Also HTML5 MovieClip extends StarlingImage and is able to change its frames.
I did not implement Starling juggler, as I don't use it in my projects, never happened to use the animated sprites 🙂