"Cities and states are in America."
Translation:Urbes et civitates sunt in America.
We should be able to use the 'que' postpositive as a conjunction, not just 'et'.
You're correct. Please report it, especially since the course is in beta.
The -a to -ae change is an exception, called the locative case, used for cities. Countries use a prepositional phrase: in with the ablative case of the place.