The Blood-Cooling Charm was invented for the story specifically to offer a means of murder that didn’t set off the wards until the point of death; furthermore, if a professor (Quirrell) cast it, the wards wouldn’t trigger anyway.
Well, yes, but it had to be believable that Hermione had cast it, therefore we can assume that it would not have triggered the wards even if Quirrel had not cast it.
The Blood-Cooling Charm was invented for the story specifically to offer a means of murder that didn’t set off the wards until the point of death; furthermore, if a professor (Quirrell) cast it, the wards wouldn’t trigger anyway.
Well, yes, but it had to be believable that Hermione had cast it, therefore we can assume that it would not have triggered the wards even if Quirrel had not cast it.