Humans think with language. Anything that can be understood can be written in language. The README acknowledges the need for further research and development but it's not hard to imagine how a more complex query could be written in English.
"How many bridges are there that are in the same state as any bridge designed by O.H. Amman and are shorter than the number of kilometers between the Earth and the Moon divided by the number of people living in the state and have a maximum load that is at least as great as the combined weight of all currently living Asian elephants?"
When someone walks over and asks, "What does this query do?" Do you just tell them that it cannot possibly be put into English? Of course not, knowing the answer and knowing how to say the answer in at least one human language are the same thing.
"How many bridges are there that are in the same state as any bridge designed by O.H. Amman and are shorter than the number of kilometers between the Earth and the Moon divided by the number of people living in the state and have a maximum load that is at least as great as the combined weight of all currently living Asian elephants?"
When someone walks over and asks, "What does this query do?" Do you just tell them that it cannot possibly be put into English? Of course not, knowing the answer and knowing how to say the answer in at least one human language are the same thing.