"She is Mr. John's aunt."
I would cut the 'Mr.' in the English sentence. It is unlikely that John is a surname.
It's a bit weird, but it's not wrong to use Mr Firstname. It's kinda old fashioned or slightly childish, but some people would do it, for example, referring to a son of a family they greatly respected. The father would be Mr Surname and the son would be Mr Firstname.
Depends on the context I guess. But in this case yes because they want you to say "she is John's aunt". Not just "John's aunt"
If this was in response to a question, it would be natural to leave it out.
For an introduction, definitely. If she's within earshot when someone asks you who she is, you would make the introduction. If she's not part of the conversation at all, then you could leave it off, but it would be fine either way.
Is 彼女 kind of odd to use here? like i understand why they're calling for it, but my intuition says that it sounds like it's referring to a younger person (or coming from a very old speaker).
(i grew up hearing native Japanese spoken, but am not a native or like-native speaker)
I think that forgetting さん after John should be forgivable, just like a typo
Culturally, it's actually a big no-no to drop it unless you're close to the person and they've given you permission.
Nope. The English sentence specifically includes "Mr.", so it has to be translated. Even if it didn't, as eiluned.bubble said, it'd be very informal to call someone by name without さん or something similar after it.
I have the answer correct letter for letter but it told me I was wrong. was it because I used the ”おば” and "さん” in different tiles? I dont know what I did wrong.