This is nothing that might merit a reject, but I notice that the -dbg package only depends on the core package. Are there not debug symbols provided for everything else? See the -dev depends for comparison:
qt3d5-dev : (Depends) libqt53dcore5 (=5.5.0-1), libqt53dinput5 (=5.5.0-1), libqt53dquick5 (=5.5.0-1), libqt53dquickrenderer5 (=5.5.0-1), libqt53drenderer5 (=5.5.0-1), qtbase5-dev qt3d5-dbg : (Depends) libqt53dcore5 (=5.5.0-1) Please have a look and fix if needed. Scott K