I have said something similar and I am English.
Someone said, "Good morning." They were wishing that I have a good morning. I pretended to misunderstand and think they were saying it was a good morning. I said, "Well, it is a morning."
Perhaps I should write sitcoms for Finnish TV.
Why always the "Well"?
In Finnish, its common to reply with the same greeting without the adverb, e.g.
Hyvää iltaa - iltää, there is absolutely no need to obfuscate the sentence with "No" Wel, its not a language construct, nor is it something that is said as default in Finnish greetings.
Hyvää iltaa and Iltaa both mean the same thing: Good evening. Many times, the 'hyvää' is droppd, but implied. If you were being literal, it coudd be funny, but it is usually just dropped for ease of articulation/simplification.
This is the case with many of these common greeting phrases.
"Good evening. Well, good evening." should be accepted. You've taught me in many a previous lesson that iltaa MEANS "good evening". So when I saw "Hyvaa iltaa" I was a bit confused... But, I'll roll with it. However the rest must be made consistent. An acceptable translation either MUST be "Good evening. Well, good evening." OR you must go back and change EVERY previous instance where these lessons insisted that Iltaa = good evening to accepting the answer of Iltaa = evening.
I don't mind the meaning being a little odd. I mind the inconsistency that I would be marked incorrect if I translated iltaa in previous lessons to "evening" whereas here, I am marked incorrect when I translate it to "good evening".
Finnish doesn't owe English any favors to understand it, so I don't understand arguments for it not sounding natural. It doesn't matter how bad it sounds in English, people actually do reply with this in FINNISH. Of course we don't say "Well, Evening" as a reply in ENGLISH, but arguing what sounds better in English isn't going to help anyone learn Finnish.
These awkward translations are not here by design, but are simply careless mistakes. In a few instances, moderators have admitted as much. The course is in Beta and they have been fixing these as they go along. It does no favor to learners to have the English not make sense when a more natural translation is available. And to expect learners to regurgitate this broken English verbatim or be marked wrong and miss points as a result is actually really poor teaching, no matter how you look at it. So, in a certain respect, the content creators actually do owe English that favor.