The first two books in the series are combined in Emily Rodda's Raven Hill Mysteries: Ghost of Raven Hill/Sorcerer's Apprentice, which also shows the pattern of having each book narrated by a different member of the team. The stakes are high enough to be interesting, with arson and sabotage in the first book and violent muggings and kidnapping in the second, but with enough daily concerns to pretend that it's all possible in everyday life. I've offered it to X, but he isn't nibbling because there seem to be no dragons involved. He also doesn't think that liking one book by an author has any connection to reading other books by that author. He's a bit dim that way, but he's cute to have around the house.
The setting confused me. I know Emily Rodda is Australian, so I assumed the books were set there. A few clues in the text make it seem Australian, or at least not American, but then the kids refer a few times to a character's dad coming "from Australia" to visit. But no one seems to think that is a particularly big trip. I appealed to the Internet, and the books were originally in Australia with the dad in America, so I guess when they were reprinted here they just flipped the dad's location. Which is amusing, because it doesn't actually work. But it turns out there are dozens of these books, some written by contract writers, and it's like an Australian Nancy Drew or something, which seems quite fun. B