"My aunt is nice, not strange."
Translation:Mia onklino estas afabla, ne stranga.
Then why on Earth is selecting the 'polite' version marked as wrong? Time and again we are reminded that we have to be as little as possible in translations, except for those cases where we aren't supposed to be...
afabla = friendly, good-natured, afable
agrabla = pleasant, enjoyable, agreeable
Both are quite similar and can mean "nice".
I'd explain the difference when describing someone as "afabla" being an outward nice or kind, extroverted nice. While "agrabla" is a more passive nice, introverted nice.
I don't believe so. You'd have to reword the second part as well, which would turn it into a separate clause, which I believe requires a connector and its own subject pronoun, which would most likely take it too far away from the original for Duo to still consider it an acceptable translation:
Mia onklino afablas, sed si ne strangas.
(Grammar note: "si" is not a typo; it's the reflexive, which here stands for "she herself".)
Note: "Malnormala" is not accepted as "strange". I guess it would be more akin to "abnormal".