I have been in the audiovisual industry for 35 years and over and could never find a free software, library and cable list to help designers create meaningful design diagrams for a lesser cost.
I am looking for people willing to set up and contribute to an audio visual device library for all AV designers to use and share
From the screenshots i see of that program it looks like visio, DIA and maybe even inkscape could be alternatives (looks like a generic system level drawing program with specialized symbol libraries.)
This of course assumes that these diagrams are meant to be looked at and not to generate some further data. I fear this will also be about the maximum that one could expect kicad to do for this usecase without at least needing to program a netlist converter.
Other options could be tools like E-Plan that could then create a cable list as requested in the original post.