Currently the com.endlessm.ParentalControls D-Bus interface
definitions and the polkit policy are provided from the malcontent
package. This is wrong, though, as the interface provides an
account-service extension that's managed entirely from
libmalcontent-0. The malcontent package provides the malcontent-client
CLI tool, but most programs such as flatpak and gnome-control-center
use the libmalcontent API to access the parental controls data.
Without the D-Bus interface files this functionality is broken.
I suggest moving these files into the libmalcontent-0-0 package.
Another option is to have a separate malcontent-data package, but IMO
there would be little to gain by just having the interfaces separately
installable.