I had a long conversation in their office, about 2 hours, mostly in Dutch (the company told Dutch is important, but not required for them). They told me they are impressed with my experience and don't doubt my expertise, but the language level is something they need to discuss. After a month, I received a rejection.
But the conversation was good, I felt welcomed and values during the interview.
Interview questions [1]
Question 1
Spreek je Nederlands? Het was de belangrijkste vraag.