"Tree swing" seems fine to me (native speaker as well), the commonality of all pictures is it is a swing, set up in a tree (albeit incorrectly or poorly in many

"Tree swing" seems fine to me (native speaker as well), the commonality of all pictures is it is a swing, set up in a tree (albeit incorrectly or poorly in many cases). If I google "tree swing" it is clear that this is not a particularly rare way to refer to this specific sort of swing.