Translation:I did not see the house in the mist.
The hints incorrectly suggest fog and haze as translations of la brume.
Mist (brume) allows visibility of 1000 metres to 5000 metres. When visibility is less than 1000 metres it is called fog (brouillard). This distinction is the same in French as it is in English.
Stative verbs (including sensory verbs: see, taste, smell, feel) are generally not used in continuous tenses. https://www.thoughtco.com/differences-between-action-and-stative-verbs-1211141
Aaaaaah, why is 'brume' first translated with 'haze' and then a sentence later with 'mist'?! Can someone please correct this? Mist and fog are caused by water droplets in the air, and the only difference is how far you can see. Haze is the reflection of sunlight off air pollution, while smog is what happens when pollution causes low-lying ozone.
I think this conversation heralds the end of the line for me. An argument about meteorology, then a discussion about stative versus active verbs, when all I am trying to do is to communicate with French speakers, most of whom wouldn't have the faintest idea of what you are talking. Most native English speakers, US and UK, would not understand such grammatical niceties either. To get by in France I don't need to know five different ways to say the same thing. One will do. Je n'ai pas vu. Who is Duo's audience?
I am not sure to understand all your points. Just for you to know, as a native French speakers, I have followed this "French course for English speakers" because it is a good way to improve English. Duo is much tolerant with the learned language than with the support language. This is why you can see questions and discussions about the English language and not about French.