What foreign children's novels are about several children taking risks together?

It's always the children who go to their relatives 'houses for the holidays and play with their relatives' children
One was that the house was sealed by the heavy snow, and the private tutor was a bad person who wanted to steal things. There were some traps, treasures, and secrets in the house.
The other was about a few children who went out to sea or found an island or a boat.
There was one where the vacation was canceled because the mother had scarlet fever and was sent to the children's relatives 'home.

Answer 1

I recommend Trial of the Goddess to you! This novel told the story of ordinary transmigrators growing up and living in the magical world. Little Ao and Little He, the two naughty children, lived happily, studied, and took risks. Together with the cunning Little Ji, they guarded Saralova. They had experienced the trials of the temple together, such as the trial of the gods. Their mission was to carry out dangerous missions in the other world, overcome all difficulties, and become good friends. I hope you like this fairy's recommendation. Muah ~😗