If that message repeats itself for every library item, you're in trouble. Your restore didn't work as it should. Most library objects have a .gsm extension to their file names, seems the dot's been exchanged to a slash?
I would try to re-install Archicad with its libraries from the original CDs,and then download and apply the appropriate hotfixes. And pray that I've got a good backup for the office's own library parts.
AC4.1-AC26SWE; MacOS13.5.1; MP5,1+MBP16,1