I have the same questions and was just writing them to ask...

What did this spy look like? Was she tall or not? Broad or slight? Was hers a high-treble voice? or a low-pitched one?

It couldn't have been Aurora Sinistra, as she's out of the castle at the moment. And must have been someone who knew that Alecto's left. Off to visit the other one, presumably.

As for Alecto, it's quite true that she's ill. Won't let me near her, however, and I've not pushed. If she chooses to suffer, that's her lookout.