Great mission! Loved the atmosphere, especially in the sealed wing. The architecture and attention to detail were superb. The ambient music was a little overbearing so I had to turn down the volume a little, but other than that, I enjoyed every minute of this.
On my way back out of the sealed wing I just bolted with the lantern on. Got chased out, but I didn't have to wait for the sister to escape for the next scene to trigger. Perhaps that could be adjusted to wait on your sister to exit to ensure she gets out safely?