Are the js tree categories populated from pulling from the SDC or DEF code?

I am trying to change the categories which appear in the category tree on the /catalog-search page. It would be helpful to know if the API is pulling from the SDC or DEF code. I am told we cannot change SDC, but we could possibly change DEF.

If anyone has any other methods for changing these categories, please let me know. I feel like I am banging my head against the wall at this point