All the names on your list are pretty, I would go with [name_u]Eloise[/name_u] or [name_f]Josephine[/name_f] though as [name_f]Isla[/name_f] is very popular. My personal favourite being [name_u]Eloise[/name_u].
One idea which you can just discard me now if you aren’t a fan of religious meanings, is the name [name_u]Genesis[/name_u]. God created the rainbow as a symbol of His covenant with [name_u]Noah[/name_u] in [name_u]Genesis[/name_u] so I thought maybe that could work for a religious family.
[name_u]Eloise[/name_u] and and [name_f]Josephine[/name_f] have some significant hiccups in the name, so we are trying to figure out which one works best for our family.
We are not religious, but if we were, that type of connection would totally work for our criteria.
[name_f]Iris[/name_f] is one that hits the meaning, but doesn’t work with any of our name choices.
[name_f]Iris[/name_f] came to mind immediately. [name_f]Iris[/name_f] [name_u]Eloise[/name_u] or [name_u]Eloise[/name_u] [name_f]Iris[/name_f] would be beautiful.