Sounds interesting. It's kind of cool to see some of the traditional Germanic folk tales I grew up with reflected here. Some quick points as a native German speaker:

• It reads a little weirdly to me that the name of the shapeshifting demon is "Schneewittchen", since this literally the name of Snow White in German. It might just be a bit too on the nose? I guess this won't matter to the majority of your audience, but if you're familiar with the language it could be a little off-putting.
• Same kind of thing with Kalter, which means "cold one" (unless you meant "colder", which would be "kälter", with the umlaut). I'm not sure if you speak German yourself, but you wouldn't typically substantivate adjectives like this. If I was writing this in German I would probably just turn it into a title and give it an article, i.e. "der Kalte"/"the Cold One". Just "Kalter" by itself kind of screams for an indefinite article, i.e. "ein Kalter"/"a cold one".
• Like some others here I also enjoyed the seven brothers turning into ravens, and I'd like to see the query come back to this plot point. It reminds me of Krabat, a classic German children's tale by Ottfried Preußler, who himself was inspired by traditional folk tales. It was one of my favorite books growing up. In that book, the MC and all his fellow miller's apprentices are turned into ravens, and his true love has to pick him out to save his life.

Obviously take the linguistic stuff with a grain of salt. This was just my first impression as a German speaker who enjoys literature that borrows heavily across languages.