"– Are you hot? – Yes, I am."
Translation:– Onko sinulla kuuma? – On.
Not an expert, but I believe that "Olen" would be the answer to "Oletko kylmä/kuuma?", which is more like a "Are you a cold/hot person?" and not an actual temperature question. "Onko sinulla kylmä/kuuma?" "On" Is the closest to commonly used Finnish.
EDIT: In summary, we shouldn't translate literally everything because it often doesn't apply.
The course is still in beta, so all alternative answers haven't yet been entered into the system. I think "Kyllä on" should also be accepted, although if I were to answer the question, I'd probably say "On joo". If you think an answer should have been accepted, it's best to click the flag icon and report it. :)
I've often wondered what would happen if I answered one of these questions with the spoken form (eg. "Mä oon", "minä olen" sijaan) mut en halua tappaa sarjani. :P
Have they made the effort of inputting every variation of what could be correct that they could think up, or are they just looking only for the same vocab they are pushing in the lesson?
They are certainly inputting every variation within reason, but haven't necessarily thought of every single possibility to start with. That's why the course is in beta: users suggest further correct translations, and the team adds them.
But I think they haven't added puhekieli, as that would mean a looooot more variations too almost every sentence, and probably lead to discussions about different dialects and blah blah. I agree with this: kirjakieli is hard enough, it makes sense to get that under your belt first before you branch out to puhekieli. I know a lot of real life courses don't do this nowadays, but it certainly makes sense for a web based course.
I believe 'Oletko sinä kuuma?' would be appropriate if someone's asking if you're hot as in attractive, or if they're asking if you're hot to the touch, like boiling water.
If they're asking if you perceive your environment to be uncomfortably hot, then 'Onko sinulla kuuma?', "Is there hot at you?", is the right way to ask the question.