what points on a human boy are safe to strike
I sincerely hope this is a typo.
On a more serious note, your analysis of the situation seems spot on to me, with one exception: Taylor has refused nearly all contact with the PRT, so there is no way she could have received that training. I'm not familiar enough with the Law to say whether this makes her liable for refusing to accept the training her position as a Ward mandates, or if it makes the PRT liable for being unable to manage and train their Ward.
Another thing that comes to mind is whether or not allegations of excessive force can even be filed against Taylor. Both parties in the conflict are masked, and laws on Earth Bet seem to at least give some consideration to this. I have to wonder if Cricket would even be
able to make a case for police brutality/excessive use of force.
Finally, here are my personal thoughts on the situation, for all anyone cares:
I doubt that Taylor (or any other Ward) would face legal ramifications solely because of the brutal methods she used to subdue the four E88 capes, even if you include the unnecessary beating she gave Cricket. The fact of the matter is that she just stopped the escape of a known parahuman villain, and in the process successfully subdued an additional three parahumans from the same organization. No significant collateral damage was incurred that I recall, so there is only her actions towards Cricket that may be objectionable.
What I can see is the PRT attempting to use that last bit as their justification for bringing Taylor to heel. It is a flimsy excuse to do so, but it is one nonetheless. Whether or not they succeed in their attempts, or indeed even try, only time (and chibipoe) will tell.
I've got shit to do now, so if you reply to this and don't get a timely response, that's probably why.