Translation:They are fine.
So, is a phrase like this either a question or a statement (maybe depending on inflection)? Could one ask "Hawajambo?" and the response be "Hawajambo."?
if it has a question mark it means how are they if it has a period it means they are fine.
But presumably the punctuation is not pronounced, so I guess the interchange I asked about could occur.
Yes, clearly, but I had always assumed this was also a spoken language. In speech, there is no punctuation. Consequently, the interchange I wrote above, which, being written, includes punctuation, would make sense. This is true? This is true.
I think they deactivated their account out of shame ... lol.
I'm no expert in Swahili, but yes, I think it's with intonation. Apparently the audio is being recorded by real people so the Swahili course won't have a horrible robot, meaning when it's all there, we'll be able to hear this :-)
I have discovered that Ni- U- A- Tu- M- Wa- are Swahili's subject pronouns, but what is H- or Ha- doing there?
No, I think it means "they don't have things/issues" i.e. they're fine.... It's just the way they do it, maybe an English speaker might ask "no worries?" and someone could reply "no worries" - this would be grammatically a similar exchange, though the English version is I think much more informal than the Swahili form.