The article also notes that she explicitly stated that the abuse was not by her family or anyone in their close circle.
Yes.
If it wasn't family for family friends the Spielbergs should have a pretty good idea who they trusted their child with.
If she doesn't want to tell her parents who they should ask what age the abuse began. It would be easy to narrow down who the abuser(s) could be.
Of course, she could have mental health issues and believe she was abused. Recovering 'false memories' during therapy is all-too common.