Awesome project! What you've built is a Cable-Driven Parallel Robot, and since you are using gravity to keep the cables in tension it is a suspended cable-driven parallel robot. Using the four cables you are able to move a point in 3D space. I happen to know this because I wrote my phd on the accuracy of these types of robots and their kinematics. At that time Jean-Pierre Merlet was probably the most famous/prolific researcher on this topic (https://www-sop.inria.fr/members/Jean-Pierre.Merlet/merlet_e...). You may also have heard of a company in Germany trying to commercialize this technology on a slightly bigger scale: https://redcablerobots.com/en/. There is also a conference on these types of machines in Europe: https://cablecon2027.sciencesconf.org/ the original being organized by Andreas Pott (another high impact sholar on this).

I have not worked in this field for many years but had a fun time learning about a very wide array of topics.

> Can it kill you? no probably not. The tension limit kicks in and lets the line out if you pull too hard.

Is there a physical safety? The anchors are attached to the wall, do they release with less tension than a human airway can withstand? I have experienced injuries that would prohibit me from exerting a "backpack" of force over my head.

https://youtu.be/AWig98GVIno?t=155 might be worth looking into with regards to the descending rod, to make its length controllable without taking up much space

How does it handle the change in slack over time as the cables naturally deform?

If I had this I could get a roomba. Does that make sense?