If Alhaitham is able to get hold of one of the criminals on noticing they aren't having any trouble seeing in the dark and shake them down, is there anything he might learn from one who is more... amenable... to interrogation?

Same question goes for Diluc, tbh. He's also not above unorthodox interrogation techniques.

ADDITIONAL QUESTION; can the 'create moonlight' and 'remove curses' abilities heal or mitigate the curse caused by touching the barrier?