It's worth mentioning that one of Apache Royale's contributors tried to submit some improvements to the AS3/Flex plugin, and JetBrains rejected them. JB basically said that they didn't want to officially support Royale unless it gained more traction.
That being said, any improvements related to AIR would be for something that JB already officially supports. In that case, I would hope that they'd be more willing to accept PRs.
If they are not open to PRs, I see that the plugin is Apache licensed, so I don't see why the community couldn't maintain an alternative forked version.