Hello, I am using Qt Creator on Buster and don't see any problems on start.
BTW, why do you have /usr/lib/x86_64-linux-gnu/libLLVM-3.7.so.1? I searched on packages.debian.org and I didn't find the package with such library for amd64. Is it the old package that was manually installed or it didn't get removed on updates? -- Alexander Kernozhitsky