Why is it blå and not blåe?
Wouldn't it be "du" and not "I" because "hat" is singular?
You could be talking to a family/random group of people who own a shared or ornamental blue hat. I think I is still a perfectly valid translation
'I' is a valid translation but i think 'du' is an equally valid translation. 'Du' is marked as incorrect though. Is there a reason that 'du' would be incorrect in this case?
It isn't incorrect and should be accepted (both "Har I jeres blå hat" and "Har du din blå hat" with the latter marked as the main translation)
Translating from English to Danish is impossible though, because there is no plural "you" in English so there is no way to know.
Ye exaggerate, y'all :-D