For a testator to leave money to children, managed by a named trustee until adulthood, is common; and I'm very surprised at your lawyers criticiam of it. When out children were small, in our Wills, the Executor was also their appointed Trustee. He was our lawyer.*
From the OP, the lawyer did not criticise the will for leaving money in trust for the children. They expressed surprise that Sally would manage this money rather than the OP. In my experience, most people don't use professionals for this as they don't want their children's inheritance to be eaten up with fees. The lawyer's surprise seems to be that Sally has been appointed to manage the money rather than the OP. I would be surprised too.
seem to imply the fact the will was downloaded and printed out as a proforma; casYou ts doubt on its authenticity or validity. In UK law such formats for wills are widely available, and perfectly legal so long as they are properly signed, dated and witnessed.
Lawyers make plenty of money from wills like this. The lawyer said it was of very poor quality. Many such wills are indeed of very poor quality. And there is doubt in this case as to whether the OP's parent had capacity when it was signed. That is the basis on which the OP's lawyer is casting doubt on its validity.
The fact Sally held POA, is itself an indication of just how much effort and responsibility she carried for organising your parents care and support in their last years.
Complete rubbish. As a previous poster said, it simply means that the deceased gave Sally PoA. It does not mean anything more than that. She may have organised care and support for the OP's parent, but it is by no means guaranteed. It does not prove she put in any effort at all.