Every bolt you could see was checked before every flight yes. Every important bolt you couldn’t see during inspection was torqued, witnessed by QA, secured via safety wire or cotter pin, and secondary torque holding was then inspected by QA.
This thing is obviously not just an interior part, look at the meat in those castings, and it’s obviously safety critical, look at the cotter pins on other bolts. Sounds like it was going to be installed behind interior paneling and not inspected every day. For something like that, every important bolt should be secured by secondary methods, torqued and witnessed installed correctly. This looks like a failure in engineering (not having wire on this bolts), then a profound failure in assembly with multiple people not doing their jobs (not torquing, not witnessing, faking logs), risking the lives of passengers.
If this happened at cruising altitude and speed, people would have died. I can’t find the flight number but I believe 9 people died when a jet lost cabin pressure and a piece of the plane while decompressing during cruising altitude over water.