In the first place, if these girls were truly being prayerful, kind and observant, they would not be acting on their same-sex attractions. Indeed, no one would even know that they experienced them. While on a purely abstract level, having same-sex attractions may not make one a terrible Catholic, in the real world, being subject to such temptations renders the possibility of true, pious practice so remote as to not be practically considerable. You will notice, for instance, that there is no known example of a saint who ever struggled with same-sex attractions. The Church is telling us something important about the nature of these sorts of people and it is for the faithful heed her wisdom and act accordingly.
Secondly, I must object to this notion that the girls in this situation are not hurting anyone. In fact, if nothing else, they are doing grievous spiritual harm to themselves, each other and every other student that they come into contact with. The temptations that these girls experience and have made public ought to have a swift and severe response administered in environments such as a school. This is the best way to teach the rest of the student body exactly how unacceptable these temptations are and will guard against a blasé attitude to such issues.
Finally, you ought not construe my meaning to be that such individuals as these girls have rendered themselves unqualified for a Catholic education in an absolute sense. I only mean that they be absent from those schools run by the Church to whom parents have entrusted the sacred duty of the education of their children. Such institutions have the highest moral responsibility to ensure that anything that may complicate the formation of their student body be rejected. Those teaching organs that individuals, such as these girls, may feel free to avail themselves of are things such as just laws passed by the legislature and enforced soundly by the courts; psychologists, psychiatrists, other health professionals or mental infirmaries; and, if it comes to it, the penal system.