I think, since you’ve already gone with short nature names for your previous two girls, you should try to stick to that - not because I think sibling names have to match, but because you should run with it if you’ve already got a theme going. Your baby girl from the [name_m]Congo[/name_m] may already feel a little different from her big sisters, no reason to give her a name that makes her stick out even more.
I’m not a fan of [name_f]Rose[/name_f] with [name_f]Wren[/name_f] and [name_u]Sage[/name_u], but not because it’s too feminine (I don’t really see [name_f]Wren[/name_f] or [name_u]Sage[/name_u] as boy names) but because it’s too common. I love [name_f]Rose[/name_f] as a name, but it just sounds ho-hum next to [name_f]Wren[/name_f] and [name_u]Sage[/name_u]. I think this extends a bit to [name_f]Iris[/name_f], [name_f]Violet[/name_f], and [name_f]Hazel[/name_f] - they are kind of popular right now, too. I also don’t like [name_f]Faye[/name_f] - just a personal preference, but you also lose the nature-feeling.
I really don’t like [name_u]Elm[/name_u] as a name. It feels a little short and unfinished for some reason. Also, depending on your accent, it’s a bit weird to say. It leans more towards the masculine, as well, like [name_u]Spruce[/name_u] or [name_m]Birch[/name_m] or [name_u]Oak[/name_u], unlike [name_f]Wren[/name_f] or [name_u]Sage[/name_u], which I feel are definitely more feminine.
I really love [name_u]Lake[/name_u] and [name_u]River[/name_u]! Also, you have a bird name and a plant name, so a water name fits right in. Here are some more options, favorites starred:
[name_f]Wren[/name_f], [name_u]Sage[/name_u], and [name_f]Henna[/name_f]*
[name_f]Wren[/name_f], [name_u]Sage[/name_u], and [name_f]Topaz[/name_f]*
[name_f]Wren[/name_f], [name_u]Sage[/name_u], and [name_f]Opal[/name_f]
[name_f]Wren[/name_f], [name_u]Sage[/name_u], and [name_f]Briar[/name_f]*
[name_f]Wren[/name_f], [name_u]Sage[/name_u], and [name_u]Bay[/name_u]*
[name_f]Wren[/name_f], [name_u]Sage[/name_u], and [name_f]Fern[/name_f]
[name_f]Wren[/name_f], [name_u]Sage[/name_u], and [name_f]Fawn[/name_f]
[name_f]Wren[/name_f], [name_u]Sage[/name_u], and [name_u]Rain[/name_u]
[name_f]Wren[/name_f], [name_u]Sage[/name_u], and [name_f]Clover[/name_f]*
[name_f]Wren[/name_f], [name_u]Sage[/name_u], and [name_u]Dune[/name_u]*
[name_f]Wren[/name_f], [name_u]Sage[/name_u], and [name_f]Snow[/name_f]
[name_f]Wren[/name_f], [name_u]Sage[/name_u], and [name_f]Lark[/name_f]
[name_f]Wren[/name_f], [name_u]Sage[/name_u], and [name_f]Star[/name_f]
For what it’s worth, I’m really in love with the idea of [name_u]Lake[/name_u]. I think it’s perfect for you and your family.