A simple solution to the problem of access is to set an accessible property from your hierarchy with the id of the inaccessible item when you do have access to it.

import QtQuick 2.9
import QtQuick.Window 2.0
import QtQuick.Controls 2.2

Window
{
    visible: true
    width: 200
    height: 200
    id:root
    property var anAccessibleItem
    Item
    {
        Rectangle
        {
            width: 100
            height: 100
            color: "red"
            MouseArea
            {
                anchors.fill: parent
                onClicked: console.info(anAccessibleItem.anInt++)
            }
        }
    }
    ListView
    {
        header: Item
        {
            Item
            {
                id: imnotaccessible
                property int anInt: 3
                Component.onCompleted: root.anAccessibleItem = imnotaccessible
            }
        }

    }
}