What should i do? (TW: Abuse)

So im 13M traveling in Russia to see my extended family, and when me, my brother, my cousin and my cousin's friend.

Were walking to a park we saw a kid and a mom walking by. The thing is, the kid was crying (They were around 4-5) And the mom was saying "Shut up" in Russian, but the worst part is when the mother hit the kid hard on the back, and the kid started crying even more. But thats not all, when they were leaving the mother said "When we come back your dad will hit you harder". (YES SHE ACTUALLY SAID THAT).

So like any rational teen i came home and dialed the police. The dispatcher asked for my Name, where it happed e.s.t. And said that they will send police to the scene.

But when I told my cousin she said that "You will go to prison if they don't find anything"

I, respectful started regretting what i did so i asked my grandma for advice, she said that i did the right thing but said that the police probably wont do anything. (Because i only witnessed it without documentation)

So now im scared that ill be locked away, and im a good kid, ive never even got detention in school.

I just need advice. I tried contacting CPS but the call didn't go through. Anyone that might help please do.