>> Sketch made <<

Squee! I'd love to see the sketch. This has been a very popular poem and I think folks would enjoy watching the art evolve.

>>(and fitting five in was hard, with that assuming magically-supported rather than naturally flight-capable wingspans!),<<

You know, I'm not sure if the humans can fly? If they can, they must be doing it with grace; you made the right guess regarding wingspan. They're big, but not big enough for aerodynamic flight.

>> probably going to be loosely watercoloured <<

That sounds lovely.

>> - I take it some gender-confused plumage is fine? <<

Yes, that's fine. Those species of parrot have low sexual dimorphism anyhow, if the articles and images I researched were accurate.