Here’s what I was able to get of August’s & Mother Superior Conversation in S01E19:
August “I understand (that’s how it has to happen– these + a few more words in the middle of the sentence afterwards are drowned out by the score & I cant quite make them out), I cant do anything while my body …”
Mother Superior “Just don’t do anything rash- Please, just tell me you’ll come to me before you think of doing anything else, then things will work out”
August ” Thank you”
Mother Superior “Oh Kay”
Since August was keeping well away from Gep at this stage & he had just been into Rumples store/office, it follows they are talking about August trying to get the knife & so Mother Superior lied to Gold/Rumple when he came to her directly afterwards (not very nun like! lol) ….. I cant see how else it would fit, unless he was trying to get someone (aka mysterious stranger) to come to SB at that stage- but I doubt it, as he was focused almost entirely on not becoming a man puppet at this point :p
Mother Superior had to have been aware of the curse in order to have had ‘that’ type of conversation with him (esp with the ‘while my body’ comment in there), or even if it was about Emma not believing- either way it appears Mother Superior has had her memories intact to some extent, if not from the very beginning then from at least when Emma arrived, so I’m thinking maybe if Rumple/Gold didn’t give MM the book, then the BF/Mother Superior would have.
Something else I just thought of was maybe their ‘religion’ had her following/waiting for the savour, maybe she had a way of keeping who Emma was with her, which allowed her to track her & so find Henry.