5th Floor Flooring Foundation question

I know I am not technically supposed to post here but I don't know where else to turn.

I live on the 5th floor in a New York City apartment and recently one of the posts of our bed frame went through the floor. They came up and inspected it and said they would fix it, but they made it seem like they were only going to fix the part where the post went in.

I did some exploring of my own, with the help of a mirror and saw that the foundation (or whatever solid thing) doesnt go to the wall the entire width of it. The walls in the corner are starting to crack where they come together too, which i suspect is tied to the floor.

I have attached some pics that show the damage and underneath. The one of the underneath has the wall on the left and the "foundation" on the right.

Basically i just want to know if this is normal and if not, who should i contact. I am feeling very unsafe up here as of now. Thanks for reading!!!