Does an actual person come up with these sentences or are they randomly created by a program
It's an actual person's job. The course was made by community-minded volunteers who gave a lot of their time (without any monetary compensation, of course) to make sure you have the opportunity to learn a new language for free.
Rome wasn't built in a day?
In Portuguese, "Roma e Pavia [another city in Italy] não se fizeram num/em um dia".
I guess he wanted to ask what this sentence shall express