(Disclaimer: I'm a Haystack maintainer and I helped creating this demo)

I had to try it out the questions you asked, because your first seems totally answerable to me. And indeed I do get the right answer in the first position (60 million). Did you ask exactly the same question you posted?

For the second, unfortunately we included only country pages and capital city pages, so it's likely that the information about the population of Cambridge simply wasn't there.

In general though I agree this task is not perfect for a demo. It's hard to tell whether the model is wrong because it doesn't have enough info, or whether it does have the data but couldn't find it. The best way to evaluate it will always be to try it out on your own data :)

Yep, that's definitely this challenge with commonly available models. In a real-life product development there's most often an important step of evaluating the model(s) and fine-tuning if necessary.

Re "Kingston" - interesting! :) Probably, because of "Cambridgeshire"?