I think this is really interesting, because "the enemy landed several of our aircraft(s)" is the sort of sentence I'd have hauled a student up for using as a teacher, because 1) it's a none standard, arguably incorrect usage they've used either because they're a none native speaker or because they're trying to be clever and failing, and 2) because the plural of aircraft is aircraft. Nevertheless the author of this sentence almost certainly meant land to mean something different (shot down) than the author of the first, and we can infer the author's intended meaning despite the none standard usage. This poorly written sentence is the sort of thing you see all the time in the real world, especially from none native speakers, children, and people writing about a topic outside their expertise. If a program can spot the difference in the usage of the word land between these two sentences and infer what the intended meaning in the second sentence is, then it's doing pretty well. Just inferring that land is used to mean something different in the two sentences is less impressive but still pretty cool and I'm not sure which claim is being made.