In order to debug translators and being able to step into glibc during it, you need the hurd-dbg and libc0.3-dbg packages installed. If you need to debug the initialization of the translator, start the translator like settrans -P /foo /usr/bin/env LD\_LIBRARY\_PATH=/usr/lib/debug /hurd/foofs. The -P option will make it pause and you will be able to attach GDB to the process.