Thanks you so much for the replies!

Now that holiday season here is over I managed to talk to the elevator company asking them to adjust the brakes, and they said they did that "to the maximum" last time they came after I complained about the noise.
They also said acoustic walls don't work so well in these cases, but that a newer machine would be totally quiet - but that would cost 8000$ for each elevator

Regarding safety:
the room used to be locked many many years ago but the door is hacked... there's inspection every 6 months (as the law here mandates) but they don't fix it. There is not even a warning sign.
Still, I had a feeling it's dangerous so I was careful... anyway I would never get up there again after what you wrote.

There were far worse safety issues in this building: several years ago 19 teens crammed into the big elevator to get to a birthday party. From what I heard the elevator was falling for a short time... luckily no one was hurt. That elevator has a door for extra room which is supposed to be locked but was hacked, that's how so many were able to get in. At least the elevator company fixed THAT door.