The genre is fine. The actual worldbuilding (if it can even be called that) she did was atrocious.
“Let’s put the secret entrance to our magical train platform right smack in the middle of London’s busiest train station! Make sure the [slur] don’t see you!”
“Let’s use owls, some of the slowest birds ever, as delivery system.”
"The bank is just actual vaults with piles of money and being run by Jewish caricatures."
“Let’s put our teleportation system in a fireplace, so you can risk getting grievously burned if something goes wrong and you carry ash everywhere.”
“Forget electricity, we’ll light up our ancient castle with floating candles that can drip wax everywhere.”
“Let’s have movie stair cases with no safety mesure in our school for children.”
“Let’s teach children how to make mind altering potions!”
“Let’s give a time travel device to a girl so she can get extra credits.”
“Let’s put all the supremacists jerks into one house and all the reckless holier-than-thou types in another one.”
“Here’s a game where children hit each other with sticks while flying 20 feets in the air and the points don’t matter because Potter keeps catching a friggin’ gold ball.”