why is "outside I see big airplanes" not correct?
It's correct and should be accepted as a valid answer; report it the text time you see this sentence.
It's a bit less natural tho.
I don't think how natural it sounds matters. If it follows the rules of English grammar, and Hungarian rules for that matter, I would report it as correct, and thus report it.
Aircrafts should be accepted too.
The plural of "aircraft" is "aircraft", no "s" ...
Yet 'I see big aircraft' was marked as error?!?
Report it :)
It almost sounds like nagyon in that sentence. I had to play the audio a few times,