I am very doubtful whether "Ile des Cygnes" is within the inscribed area of Banks of Seine. This year's WHC document clarifying boundaries doesn't include Paris so we only have the evaluation docs to go by. The Ile reaches as far upstream as the Pont de Bir Hakeim which it goes under by a few meters and this bridge IS next to the RER station for Champs du Mars/Eiffel. BUT I believe that the inscribed area of Champs du Mars and Trocadero is slightly further upstream on the Pont d'lena axis. The evaluation document states clearly "The choice of the zone between Pont de Sully and Pont d'lena is based on the age-old distinction between Paris upstream and Paris downstream."
Wiki also states of the modern Ile des Cygnes "It should not be confused with the earlier Īle des Cygnes, from which it derives its name; the earlier island was attached to the Champ de Mars in the late 18th century." As with Tenochtitlan we are "allowing" former artificial islands but there is no evidence is there that this former manifestation of the "Ile des Cygnes" was artificial?
(PS If my assessment is correct then the Statues Connection shouldn't mention the Statue of Liberty for Paris - Banks of Seine since the small replica is on Ile des Cygnes at the far end from the Eiffel Tower facing west)
Never mind - it is an interesting "Connection" and we can still have the required 3 by adding Pampus from the Amsterdam Defence Line - an artificial island built originally on a shallow in the Zuider Zee!