sometimes you just gotta do what you gotta do in order to survive, if you get what I mean fam. One wrong sentence can get your whole family tree beheaded right! isn't it Chinese drama type of thing LOL. hope you get it.
I get what you're saying about Elder Asian are too old school. I will put it this way. Imagine a mother who has been away from the child for so long plus she doesn't have any other daughter beside CSS, she must have felt awkward in what way to express the way she intended to as a mother. as a metaphor here, you're a fresh graduate person and even you know a lot of theorical field, but when you start your hand on job, it will always have flaws and awkward moments before you can get used to it. I'm not trying to stereotype, but I'm also Asian and that how I feel about my family. we don't randomly say I love you to each other, but when it comes to trouble or issue my sibling don't even need to awkwardly ask for help, but we just voluntarily help with love and smile.
For Asian's caring is not just by the saying "I love you blah blah", it showed through intention and action. More than this when she said YangYang would be fine, I believe she mean she doesn't care enough about YangYang as she cares so much about CSS. It is also a flaw from her mom that she cares too much to the point that it looks like she doesn't like CSS at all, but she actually has the most love for her own daughter than her niece.
as you can say even though she is her closest niece, but nothing compared to your own blood. Motherly nature will have to be more worried and care with her own child than relative.