I have a few nieces and nephews that are 13 and while they are kids they also, to me, young adults.
So long as she has a support boat in the vicinity, I don’t think it a big deal to let her do it. Schooling can be brought up to speed relatively easily when she is done. Wish I could sail around the world. Let her do it while she can, make some money on a book.
Where did you read a 14 year old schoolboy doing that Dallen? There is only a 17 year old who was out at sea for 9 months. Can you show us the link to the 14 year old school boy who sailed for 2 years? That sounds fictitious.
Looking at an article it seems as if the people who do these "trips", do it for the money rather than "seeing the world". The 17 y/o who just did it named his yatch the name of a price comparison website.
Back to the 13-year-old Dutch girl Laura, it is unlikely the Dutch authorities who have made her a ward of the court would allow her to make the trip. I would not expect any European country to allow a minor to make such a trip, though in America anything is possible.