|"Is this all real? Or has this been happening inside my head?"
The topic of this article is of a real-life subject that has been mentioned "in-universe" in a canon source. The Harry Potter Wiki is written from the perspective that all information presented in canon is true (e.g., Hogwarts really exists), and, as such, details contained in this article may differ from real world facts.
Many Dutch witches and wizards attend Beauxbatons Academy of Magic in France, presumably due to a lack of a wizarding school in their own country. Because of this, it can be assumed that Dutch wizarding children learn French as a second language during their childhood or that Beauxbatons has a Dutch sub-division as French is not a language traditionally spoken by the Dutch.
Notable residents include the Muggle J. C. M. van Riemsdijk, who wrote a book on the history of Dutch music entitled Het Stads-muziekcollegie te Utrecht (Collegium musicum ultrajectinum): Eene Bydrage tot de Geschiedenis der Toonkunst in Nederland.