What do you mean with chomskyan sentences? Is it a sort of theory wherein you use odd sentences to get people deeply familiar with a language and its use, because to translate, people have to really think about what they are translating? Because the odd odd sentence on Duolingo has really helped me understand Norwegian more.
I can't speak to what Chomsky has to do with it, but I certainly agree that the odd sentences are a great help. For one thing, yes, you need to think about what the sentence is saying, just to be sure that it's really saying that, and I think that does help with language learning. For another, I really appreciate the whimsy. It livens the course up a lot. Often the comments on the odd sentences are worth reading as well: the whimsy is contagious!
Since the adj. "stolt" is quite similar to the italaian adj. "stolto" (lit. Dumb, foolish; a meaning better fitting in this sentence imo) I considered it to be "proud" in a negative way, like "full of himself".
Is it how it is or could also have a positive meaning of "proud"?
On the desktop version, you can read a grammar page specific to each module ("Tips"), which can be a helpful introduction prior to beginning the module. This isn't available on mobile, but when not on listening exercises, you can tap on the new words for a translation. During listening exercises, this abrupt addition can be a nice challenge for testing how well you can intuit the spelling based on what you already know. (And you can always temporarily disable the listening exercises if it gets too irritating when learning new vocab.)