[elif]

Ehhh it's definitely nuanced but we certainly haven't been dramatically overlooking anything fundamental.

The prevailing wisdom has been that a fully developed cockatoo has roughly the intelligence of a 3 year old.

A 3 year old figuring out how to use a drinking fountain wouldn't be world-breaking science, and I don't think this is either.

We have proven that they don't understand language and can simply mimic sounds. I don't think it's as deep as you are hoping.

[teaearlgraycold]

Could they have their own language though?

[elif]

Cockatoo language in nature is this:

Child: wild call

Parent: wild call back

Child: wild call back

Parent: wild call back

Child: wild call back

There are bird species with nuanced dialogue-like calls, but parrots are not him ...

[xeonmc]

And, occasionally, demonic summoning chants:

https://www.youtube.com/watch?v=5UUjJysUMTw

[ImaCake]

While their calls sound like chalk on a blackboard their body language is complex. You can communicate a lot via your actions and expressions!

[SAI_Peregrinus]

African Gray parrots have been proven to understand significant amounts of language.