Following Buster's departure in Season 2 to live with his father, Bo, Buster comes back during Season 3 and his return flight lands here, because it is the closest airport to Elwood City.
Buster, D.W., Arthur, and the Read Couple flew out of this airport on their way to New York City.
The "Katzenelenbogan" is most likely spelled with one 'L" because the creators of the airport must've taken reference from the monument (which had also spelled Jacob's last name wrong) and thus, "Katzenelenbogan".
According to the map of Elwood City and Crown City, the airport location could be a reference to Montréal–Pierre Elliott Trudeau International Airport.
Based on its' name, the airport could also be based off of Logan International Airport in Boston.