[DiapDealer]

If you're starting Sigil directly using /usr/lib/sigil/sigil, you'll need to manually set the variables that are set in the launch script /usr/bin/sigil. Otherwise, as you found out, it won't be able to find libsigilgumbo. Nothing is corrupted. The launch script prepends /usr/lib/sigil/ to LD_LIBRARY_PATH. Binaries in Linux don't automagically find/load shared libraries just because they're in the same directory.