Do the two children who were beaten in Quran memorization circles have a right against the teacher, knowing that one of them was recommended to be beaten by his father and the other was a troublemaker and assaulted another student?

There is nothing against you, God willing, for a teacher's striking of a discerning child for the purpose of discipline is permissible, especially if it is with the permission of his guardian. The same applies to striking a child if he harms others. It is stated in Ibn Sahnun's "Adab al-Mu'allimin" (Etiquette of Teachers): "It is incumbent upon the teacher to discipline children if some of them harm others."