The word "Lunch" means a meal taken in the middle of the day, and is a valid term in any english speaking country. It's not more American English in the slightest.
"Dinner" means the main meal of the day, so for some people/communities who do or in the past had their main/largest meal in the middle of the day they may have adopted the term dinner for their midday meal. Though if this is not their main meal of the day then they're wrong and using the term incorrectly.
I had the same experience, but I grew up in the American South in a small town. The mid-day meal was dinner, and the evening meal was supper. The ancestors of the people in my town came from somewhere in Great Britain before the 1700s (we have not been able to trace the exact locations.) I wonder if they brought this custom with them? Language study is so interesting.
I have trouble with this constantly.
Growing up, I was always taught in school (since my earliest years), 'The three meals of the day are breakfast, lunch, and dinner.' I also know that 'supper' is another term for 'dinner'. This is common in many English-speaking countries - so it surprises me that the middle and latter meals would have trouble being called the same thing.
To me, 'dinner' is the evening/night-time meal, and 'lunch' is the mid-day meal; however, in the part of the state I'm living (which is WI in the US), people here are always calling lunch 'dinner', so I'll assume they mean the evening until I'm corrected.
I've been late to a few lunches because of this (it doesn't help when the person won't specify a time & says they'll get back to you but doesn't).
If Duolingo is using a specific dialect of French it should be marked clearly - I've NEVER heard the word petit-dejeuner, but dejeuner means breakfast and I've been marked wrong here, apparently because Duo uses Parisian French. That's fine but it should be marked clearly at the start of the program if Duo's going to use a specific dialect.
(for reference, I'm bilingual in international French and learned it in Canada, in case people were curious)
That page does not, as far as I can see, specify that it teaches Parisian French. It has some inspirational talk about France, but I don't typically assume that means you're learning a specific dialect. If the 'learn English' course talked about like, Britain, I wouldn't assume I'm learning British - I'd assume I'm learning English. :)
Would you assume that the default option of a site teaching French would be to use Canadian French? Based purely on best logic? The Spanish course based on Venezuelan Spanish? ;) I think unless it's clearly stated otherwise, you should assume a given French course uses French from France. Just sayin'
No, I would assume it would assume it would teach INTERNATIONAL French, because I would assume that is the most applicable to the highest number of people. It's literally just another word for Standard French. Parisian French is a specific dialect - it's basically the same as teaching Venezuelan Spanish :) The most applicable non-dialect version of French is Standard/International French because it's NOT based in a specific dialect/country.