Also we're not arguing the language here or its adherence to the specific reality, but the blunt tool the laws are.
Putting other countries laws aside, I believe that digitally manipulating the image of the real child in that way results in the production of the actual CSAM and as such is a federal crime.
And back to my previous comment - actual children are involved, so the abuse actually happens. If you doubt it, feel free to read up about women who experienced their own AI-manipulated pictures to make them appear naked - I don't think you deny the actual harm here.
In terms of generation (harming pixels), I think the idea of the lawmakers is to criminalise similar ones as well ("indistinguishable from a real child") to offer some protections to real children.