Was Buttons female? I'm not sure if I'm using the right pronoun.
I don't know. I used him/her then got lazy and just said him. All the cat voices sound female to me and buttons could be either.
The little girl is one of 3 prisoners locked in vaults right? The other 2 being a dwarf and a lizard. I think the lizard claimed to be Godwoken, so probably also a sourcerer.
I used an old save file to see what is said on the magister bulletin board inside the prison. I mean, I hope we're thinking about the same prison here, I went to the underground prison in Driftwood, below Magister Carver. What I read there is that there is "sourcerer activity" (or something like that) in the north of Bloodmoon Island. It wasn't referring to a single sourcerer in particular, so I think we could have multiple candidates here.
We were. The lizard was entombed long before the magisters' war on sourcerors (at least, that is what I think, an assumption I made based on what characters said) but the Advocate also had to be a master sourceror to train godwoken. I didn't consider him because he's based to the south of the island. It's likely one of those things without answer.