The cross on the tombstone is Christian Orthodox.It could be that they were buried in an Orthodox cemetery???But since they are documented as Greek Catholic (Byzantine Rite Catholic - Uniate), it will make looking for records in Ukraine easier. They are more readily available.
There should be no doubt that Danylo was from Nowosiolka/Novosilka. As per the ship's manifest, in PLACE OF BIRTH Novosiolka is listed.