The 'sound-jucer' claimed the follows at starting up with own locale (ja_JP.UTF-8):

$ sound-juicer
(sound-juicer:19434): GLib-GObject-CRITICAL **: 
g_param_spec_internal: assertion `(name[0] >= 'A' && name[0] <= 'Z') || (name[0] >= 'a' && name[0] <= 'z')' failed

So I retrieved backtrace on gdb and traced the code of BraseroDriveSelectionClass in libbrasero-media,
then I found the incorrect code with i18N:

611 static void
612 brasero_drive_selection_class_init (BraseroDriveSelectionClass *klass)
613 {
(snip)
624 
625     g_object_class_install_property (object_class, PROP_DRIVE,
626                      g_param_spec_object (_("Drive"),
627                                   "Selected drive",
628                                   "The currently selected drive",
629                                   BRASERO_TYPE_DRIVE, G_PARAM_READWRITE));

This code looks incorrect because the property name would be translated on runtime then caused above assertion. It should be

625     g_object_class_install_property (object_class, PROP_DRIVE,
626                      g_param_spec_object ("Drive",