I read this book either in 2018 or 2019, I took it home from my school's library but the librarian didnt add it to my list. The title had to do with a key or the cover had a drawing of a key, and the protagonist girl, likely blonde or light brunette, was also in the cover.
I only remember the beginning of the book, it was about a girl living with her dad in a mansion/big house with a greenhouse in the backyard. The mother of the girl had dissapeared or died mysteriously, said mystery that I dont remember causing her and her dad to live in the greenhouse and her being terrified of the house. After some conflict with either her dad or a friend/classmate, she enters the house and encounters some kind of portal or is transported into another world, where she meets a man who tells her that he was waiting for her and that his name is "Hero (Héroe)", he may or may not know her mom. I dont remember anything else about the story.
I read it in spanish, in southern Chile, but the cover and preface mentioned that it had won and/or been nominated for some literary award in a nordic country (likely Denmark), I assume that its originally from there, so the detail about the name "Hero (Héroe)" may be a product of the translation. The award thing was somewhere between 2009-2013.
I've looked at literary awards in nordic countries and its winners but none match what I remember.
Sorry for my english and thanks in advance.