But Hungarian has a word for big - nagy. Magas apparently specifies vertical extent, just like the English "tall". I'll wait for a native speaker of at least someone fluent to say anything definitive, but I'm willing to bet that this is as weird and pointless a sentence in Hungarian as it is in English.
Nothing surprises me in Duolingo anymore. In the Turkish course, there is a sentence "Everyone is looking for a pink island." Apparently, in the Dutch course, there is the sentence "In reality, I'm a duck."
You're right about that but there's a difference between semantically 'weird' sentences (like the turkish and dutch examples) and grammatically corrupt ones, since i don't think you'd say "tall" for a building in english - at least what i learned is that "tall" describes (mainly) humans where as "high" describes (inanimate) objects.