It was said that lift asked to stay the same, or remain unchanged while things around her changed, or some variation of that theme. In the released draft chapter, she is growing and complains about not getting what she wanted. I think that cultivation would never grant someone to never change, as she is a shard of growth, and the story overall would not stand for a static character. Furthermore, the saying of the oaths requires some form of growth as a person. To get around this, Cultivation might have stopped her changing physically. This could explain the conversion of food, so she can stay the same size and weight. (of course, for that, her weight at the time of asking must have been indicative of some form of malnutrition.). This i think would be the boon, or boon in addition to curse.