Please suggest me a book about a magical forest (or magical characters in a forest setting), especially if it incorporates Welsh or Slavic folklore.

Hello!

I love books with a forest setting that incorporates a lot of folklore (specifically Welsh and Slavic, though I'm enthusiastically open to any other culture). I've already read:

• Uprooted by Naomi Novick
• The Chronicles of Prydain series by Lloyd Alexander
• The Narnia Chronicle by CS Lewis
• The Woodcutter by Kate Danely
• The Wildwood by Colin Meloy
• The Bone House by Emily Lloyd-Jones
• The Bear and the Nightingale by Katherine Arden
• The Wolf and the Woodsman by Ava Reid
• The Hazel Wood by Melissa Albert

I'm not looking for anything that centers around anthropomorphic animals (Winnie the Pooh, Wind in the Willow, etc) and I would prefer it if it was at least YA or adult though I'm open to middle grade if the story is really good.

Thank you in advance for your recommendations!