^
As OP says, this girl spoke directly to the employees of this casino and they did not respond to her request. So it seems to me that without the involvement of law enforcement agencies the case will not move forward.
In general, if I were this girl I would ask someone to film minors playing in the casino and try to spread this information over the Internet. I think this kind of video would quickly find support among people who are fighting with this kind of violations.
if the girl filmed these children playing in the casino and posted it on the internet, however noble that girl's attitude is, she could be arrested depending on the country, because it is against the law to film minors who are not your relatives without the consent of their biological parents or an adult responsible for the child, what this girl could do would be to film the minors playing and take the video and hand it over to the police, that way the video would not be considered a crime, on the contrary it would be considered evidence against the casino, and the police would go to the casino to replace it. the law and would send the children away from the casino and bring criminal proceedings against the casino, and perhaps the government agencies responsible for licensing the casino would withdraw the license from the casino
but most of the time physical casinos are operated by people with great power in the government, and they are very important people who do business with the most important people so when someone with less power denounces them then that person can be at risk of life, you can even be murdered, or arrested or never get a job, bank loan or space to do business