Yes, but if the childminder took her on knowing that, then she shouldn't have and it was wrong of her to do so. She hasn't necessarily committed a crime, people are saying "manslaughter", but as you say that depends on the details.
If she's been professionally negligent though she could be sued for that and it seems pretty obvious that she has. It won't bring the child back and I'm not big in suing, my point is that she's to blame for what happened if she didn't follow instructions and agreed to take on the job of caring for this child knowing she couldn't meet the child's stated needs.
She's trained as a childminder, it's literally her job to care for children, so she can be considered professionally competent to decide whether she's able to do that, or not, for any particular child.
Cries of "she didn't know how bad the child was, it's not her fault", are bullshit. She wasn't a random friend or neighbour who may not have understood the child's needs, she's a trained professional running a business. If she "didn't know" the level of the child's needs, that's incompetence. It's literally her job to find out, how else can she expect to provide adequate care to a child?
If she thought she knew better than the parents and didn't need to follow their instructions, that's arrogance. If she thought she could do whatever suited her and nobody would find out she hadn't followed instructions, that's deception.
Whichever way you look at it, if the parents didn't lie about the child's needs and downplay how easily she escapes, then the childminder is to blame for not keeping the child safe. She didn't have to take the job on. A few questions should have showed her that.
Like -
"how do you keep your child inside at home?" We have 6ft fences and electronic door locks.
"I don't have that, is she likely to escape my property?" maybe, yes.
"How do you manage when you're out?" We don't take her out, ever. If we really really have to do something essential with her, she wears reins and we never ever let go not even for one second because she'll run off.
"Ok, I understand. I can't accommodate her needs because I have multiple children to look after and she sounds like she needs one-to-one care at all times, you'll have to look elsewhere for childcare".
How hard is it to have a one minute conversation that shows she shouldn't take on this child?
With the comments about how she told the parents she was out a lot with the children, and then took on this child who had to be locked inside, that says to me that she's tried to waive her legal and professional responsibility to look after this child properly by batting the details back to the parents. You can't sign away your legal responsibility by essentially saying "it's at your own risk". That's just tactics to dissuade people from complaining but it doesn't stand up in law. If she's running a business she ought to know that and if she doesn't know it, that's on her.
She can't blame the parents for her own incompetence in looking after their child. It's not their fault for leaving the child with an incompetent person, that might apply if they'd left the child with a friend, but they left her with a trained professional. One who, in this particular case, could have and should have carried out an adequate assessment to see if she could meet the child's needs, then declined the job because she couldn't.