I had attempted to compile and use glibc 2.29 in a separate directory on my system. This failed when I ran ldconfig and caused a very unstable computer. i finally recovered the system by using a live CD version and chroot’g into the HD where the issue was to remove a couple of things as well as re-running ldconfig.
Today, I took a differant approach and used LD_PRELOAD=/opt/glibc/lib/libm.so.6 ./Lightburn from the install directory and it worked. Lightburn 1.2.04 starts and runs with the one simple change. I’ll add it to the desktop using a command line that preloads libm and I should be able to run newer versions. I hope this information will help someone in the future who has an older system and needs to run a program using new libraries.