I agree with a lot of what you wrote. This child is particularly strong. And I'm sure she will compel herself to testify to get justice.
However, I disagree that she will march right up there and easily testify. In most cases where child victims of trauma testify they need a lot of psychological help, victim assistance and safeguards to be anywhere close to a position to be able to testify.
Also, I 100% disagree that children are resilient. I think that's something we adults say to comfort ourselves. Children are particularly vulnerable to the effects of trauma.
Almost every mental illness has roots in childhood trauma even when there are genetic components. Anxiety disorder. Panic disorder. Depression. Bipolar disorder. Narcissistic personality disorder. Histrionic personality disorder. Antisocial personality disorder. Borderline personality disorder. Obsessive compulsive disorder. Alcohol and drug dependency. Etc.
All can stem from childhood trauma.
Children are horrifically destroyed by trauma. They lack the emotional reserves, the cognitive abilities and the maturity and life experience that enables them to cope with such events.
Interestingly, the child you reference was one of psychiatrist Bruce Perry's patients. He wrote the primer (IMO) on childhood trauma.
That kid had extensive therapy in order to be able to get up there and testify, from what I recall, which mostly consisted of her repeatedly positioning the doctor on the floor and simulating hog tying him and slitting his throat, until eventually she gained some semblance of agency and power over the memories of what had been done to her.