Mathilde gave an intervieuw to the Belgian journalist Martine Tange about language/reading in the Magazine Trouw.
you can read the article (only Dutch).
Mathilde learned to speak Dutch when she was 12 years old. The most difficult where the sentence constructions, the pronunciation of the clangs and the accents.
She knows she has a French accent but she tried to improve herself every day. She reads Dutch newspapers, listens to Dutch radio, television and speaks Dutch with her advisor, assistents and friends.
At home she speaks mostly French with her childern but the childern go to a Dutch speaking school, when they make there home work it is in Dutch and they think in Dutch. The childern among each other speak French and Dutch. What she now often hears with the young childern is that they speak the both languages in one sentence (because they don't know some words in French) and that is what Mathilde tries to avoid.
She find it very important to read stories to the childern. The childern don't go to bed without a story. She also is 'reading mother' at the school of the childern. She loves to do that but she never reads to her own childern at school.
Elisabeth loves to read fantasy books, Gabriël loves Greek mythology for childern, Emmanuel does not have any favorites for the moment and Eleonore follows het sister and brothers.
Mathilde often speaks to princess Laurentien of the Netherlands about language. Laurentien gave Mathilde a copy of her book for blind childern. Both princesses share a passion for reading.
Mathilde herself loves to read in different languages. Especially during long flights, when she does not has the childern around her. She listens to other people when making her choises. She is very interested in literature, nowedays especially childerns literature due to the childern's ages.
Prince Philippe also loves to ready, more then Mathilde. Especially biographies, economic books and books from the family library.