(although in my game Sarah has already with Louthros so she's clearly not with Slayer). Here is what I did...
Hold on. I don't think you can finish Absinthe before Zanthra??
That said those events are supposed to happen more or less at the same time, so taunting Sarah could happen just before Louthros goes into rampage mode in Zanthra and gets her back.
I went to the area with the cat but couldn't defeat the cat, so I thought I'd just explore the rest of the guild/museum. I explored everything except for the raised area where the candle is. Then I tried returning to the main floor to annoy that cat again. EXCEPT when I get to the top of the stairs on the second floor and head down, I keep tripping that cutscene, which would only be a quirk, not a bug, EXCEPT at the end of the cutscene, I'm forced to face up and move up one space north. So I can't return to the cat. That event needs to have a self-switch set to prevent it from repeatedly happening.
Edit-I used the Exit Danger menu option to get me past that spot, so I was finally able to return to the cat. Still, it's a bug since not everyone may think to use that menu option as a work around.
If it's the cut scene I think it is, it should be fixed?