Royale doesn't provide the Flash API, so it will be challenging to port Starling. The best option for using Royale may be to use OpenFL and its version of Starling, both compiled to JS, and then write AS3 "externs" to expose them to the Royale compiler.
I'm probably biased, but I'd guess that it's much easier to just switch to Haxe and use OpenFL/Starling from there. It's a different language, yes, but Haxe is probably the closest language to AS3 you could find. Really easy to pick up.
Royale releases tend to be spread far apart. A lot has improved since 0.9.9 was released (and 0.9.10 is almost ready to go). It's usually better to use a nightly build. You can find them at the bottom of this page: