Some really beautiful and strong names here!
Matilda is a lovely name (I love the nn
Tilly), and I also really like
Rose,
Beatrice,
Frances, and
Miriam.
Cosima is plush and velvety. I wouldn't use it personally but I like it.
My favorite of your boys' names is
Malcolm. I think it's so strong and classic, but a little unusual in my part of the world as well. I also like
Tobias (nn
Toby),
Calvin, and
Lachlan.