"John is a foreigner."
You should use honorifics the same with foreigners as you do with Japanese people, so if the foreigner is someone you don't know very well, you should use honorifics.
I do find that because honorifics are not used in English, this sometimes gets carried over into Japanese. Even I as a foreigner often do this when speaking Japanese, referring to the other foreign teacher at my work as "Bob" when talking to students, even though I should call him "Bob-sensei". There's also this innate attitude that foreigners are open and friendly, so Japanese people often feel more comfortable calling them by their names without honorifics. It's certainly not the correct etiquette, but it happens a lot.
Having hiragana in the hover-over hints would be useful here. "Foreigner" shows "外国人" and nothing more, which .
I don't understand why they don't just make all of these hints show both words. It seems a simple and easy way to do it.
For example here, "foreigner" could show: "外国人 / がいこくじん" and this would be a best-of-both worlds. They could do this both for words where DuoLingo has introduced the Kanji, and where they haven't.
And it would require no extra programming on the backend either, it would just require entering these...and it doesn't seem like it would be that much work either.
No it's not. Suffix "よ" makes the sentence sound.. stronger and more confident, so when you say for example I need a car "車が要ります", you just make it sound like you need a car, however the listener can't tell wheter you really need a car, but when you add the suffix よ, "車が要りますよ"- you make it sound like you need a car and you are certain about it. This is however how I think it works.
There actually isn't a word in Japanese which is the adjective "foreign". This phenomenon occurs quite often where Japanese people simply use "nounの" as an adjective version of that noun. So, "foreign" would be 海外の (かいがいの, "of overseas") or 外国の (がいこくの, "of a foreign country).
Also, 外国人 is the noun for "a foreign person", so your suggested answer doesn't accurately translate what we're given.