No matter what the children did, even if they were evil to the bone, it wasn't Raguel's authority to punish them because no matter what, Heaven believed that all children had pure souls.
Their souls might be tainted by their surroundings, but they could face redemption easier than adults, which was a huge merit for people in Heaven.
Raguel could not attack Ainsley, which was why he probably assisted Michael to attack Ainsley on his behalf instead.
As for Wilhelm, that guy only had the appearance of a child, but his physical age was already older than many oldies combined.
As for Ainsley, her physical age was indeed four years old.
Even if her soul was twenty years old, now that the soul blended with the body, unless Raguel could precisely attack only Ainsley's soul, he could do nothing to Ainsley.