Translation:This is extremely spicy. Get me some water quickly!
Too / excessive = 太. Too hot = 太 辣 了.
Technically, you're right, but in their other example with 苦极了 they accept "too bitter," so for the sake of consistency and in the spirit of rewarding understanding as opposed to precise diction, "too spicy" should also be accepted in my opinion.
"this is extremely spicy. Quickly give me some water" was rejected but I think it's ok
Never drink water with spicy food, it doesn't help at all! One should either have dairy, or strong alcohol!
People do actually say this, but water does not help with spicy food, it makes it worse. What does work is liquid dairy products like milk and yoghurt, and distilled alcoholic drinks like baijiu. Fermented alcoholic drinks like beer don't work. (-:
This should be "Quickly!" in the interjection. Maybe "Quick!" is the informal/colloquial form.
"This is extremely spicy. Quick! Bring me some water" is not accepted. "This is extremely spicy. Bring me some water. Quick!" is given as the correct version - despite the word order in the sentence. Reported 8th September 2018.