One of the things that's been really important for me in planning WITMonth is that we focus not only on very Serious Grown-Up Literature, but also take a moment to appreciate books in other genres or designations. There's not much children's literature translated from other languages, but of those few books that are translated, quite a few are actually written by women.
First up is Cornelia Funke, who is quite well known as a young adult/middle grade fantasy writer. Inkheart came out just near the end of my fantasy phase in middle school, but I remember really enjoying it at the time. Somehow I managed to never finish the series, but there's no denying that she's one of the premier women in translation of the kid-lit world.
Next is Janne Teller's Nothing, a book I found as frustrating as it was interesting. It's not a perfect book by any means and its weird mix of extremely simple writing with lots of pseudo-philosophizing made me want to throw the book at the wall several times while reading it, yet it remains the only book in translation (that I'm aware of) to have won a Printz Honor. In a younger field, we also have writers like Tove Jansson, best known in literary circles for books like The Summer Book or The True Deceiver, yet known worldwide for her Moomins series.
Breaking away from Central Europe, we also have one of my personal favorites: Daniella Carmi, whose Samir and Yonatan remains the only book translated from Hebrew that I've ever read in English and not in the original (accidentally! I did not realize at the age of nine that this was a translation, and was extremely embarrassed once I identified the original in our family's bookcase). I used to reread Samir and Yonatan a lot when I was a kid - it's a powerful book that always gave me hope.
What are your favorite kids/young adult books by women in translation?