I'm a bit confused here: this character is supposedly Finnish, but that's a moose in the style of a Dalahäst ("horse from Dalarna", a region in Sweden). They're little wooden horses painted with the colourful, traditional flower patterns that are typical of that region. They're extremely common souvenirs, and are considered a national icon by Swedes; something that's so Swedish that it becomes kitsch.
Don't ask me, I know next to nothing about Strike Witches. I'm just impressed with the artist's knowledge of Scandinavian folk art, that's all. That dress is of a traditional Scandinavian style, too.
I don't know what an amalgam is in this context, but Finland ("Suomus" in Strike Witches I think) is a different country from Sweden and Norway (which together form "Baltland"). Sadly the only representation I've seen of Baltland in Strike Witches lore is a single character mentioned on a wiki who apparently transport supplies to Suomus, based on a civilian pilot that did just that in WW2.
The Dalahäst (which in this case is an elk rather than a horse...) is certainly Swedish, but the clothes she's wearing looks more like the results for "Finsk nationaldräkt" (sv: "Finnish national dress") on Google Images than it does the results for "Svensk nationaldräkt" (same, but Swedish), so I'm changing the tag from swedish_clothes to finnish_clothes. Not to mention that it makes more sense for the character.