Responses
Honestly, me neither... The translation is so vague... I thought it might have been related to what she said when she succeeded, "That succeeded!" which might have meant she doubted thinking about her mother as light would work. Realizing how it worked, she gained courage to now confront the darkness as she is now trying to move on and trust the affection her mother shows. That's my assumption, but honestly, it might as simple as she didn't think it would work.
When lyrica succeed the chant, why the emperor look her like that and said "why did you do that"? And why suddenly she's down? Sorry I don't understand that part.