Foster... The only one even remotely aware of scalegrowth is Morven, and nanotech medical care has evolved so far that its essentially considered to be perfect. The only ones who would even care about medical care of a nature not based on nanites would be extremely eccentric historians. Its similar in many ways to how many practice the arts of making flint tools in our society.

The ambiguous 'everyone' knows that nanites can cure every sort of injury/illness known to man as well as most of those unknown to man. People don't get curious about ailments... They simply take a nanite injection to fix it and go on with their life. No need to worry about it.

As for Morven's case... The changes to her body, while they are to a large degree physical, are also biochemical. As the changes occur, her mindset is similarly changed. Whatever it is that is changing her, it is also changing her so that she thinks nothing is odd about it. A bit like brainwashing, really. Its rewriting her entire DNA, one segment at a time, but in a fashion that makes it so that the nanites cannot find anything wrong, simply because there's discrepancy in it. When one segment is changed, it is done so in every cell that has record of that particular piece. Or so we understand our own concept, at least. The alien thingamajig isn't explaining everything to us yet.
DNA is supposed to be static, and the changes to her DNA are subtle, so records are somehow being updated to match her current DNA. 

Cooking, on the other hand, that can actually make sense to have someone on board with skill at. No matter how you can make a gray gooey paste (or stuff like that) provide the nutrients needed, we can't readily see a day when humans wouldn't enjoy "real" food.