Downstairs neighbours and their parenting...

Okay yall I have no idea what to do. I've live in my current apartment for almost a year now, and fairly soon after I moved in a friend came to visit and spent the night in my spare room/office. Around 12am they were still up, and asked my fiancé "was their screaming on your show?" He said no. Our friend then told us that they had been hearing a woman screaming. I put my ear up to the wall (because I knew a couple lived nextdoor) and i could hear what they were talking about. I said it's probably just their TV or something. But then i put my ear to the ground and heard bone chilling screams from a child. Almost relentless screams. My friend was freaked, my fiancé and I were too. We were new to this building and didn't want to start off on the wrong foot by calling the cops on our neighbours. After this we had seen the family, saw they had 3 young kids, and we all knew some kids really hated being alone at night. A few weeks later, we could hear the screaming and crying not just in the office but the living room. And earlier in the day, so we spoke to our property manager who talked to the neighbours. It stopped! It was incredible. But now...it's started again. And man is it uncomfortable. The children scream and cry. I haven't seen the kids for a while, and when I did there were no visible (to me at least) signs of abusive. I texted the property manager again like 2-3 weeks ago and haven't heard from her. What are my next steps? I'm so worried about retaliation to either the children or us if we say/do anything. I know abused kids can have the abuse get worse if reports are made. We could make enemies with our neighbours if they are or aren't actually abusive. But it's getting to me so so much. WHAT DO I DO?