Some Myanmar glyphs are rendered incorrectly on QML app

import QtQuick 2.0
import QtQuick.Window 2.0

Window {
    visible: true

    FontLoader {id: fontL_my; source: "file:///home/seonmi.jin/aajin/NotoSansMyanmar-Regular.ttf"}
    FontLoader {id: fontL_km; source: "file:///home/seonmi.jin/aajin/NotoSansKhmer-Regular.ttf"}

    width: 500
    height: 800

    Column {
        spacing: 10
        x: 20

// QtRendering ---------------------------------------------------------------------
        Rectangle { width: text1.width; height:text1.height
            Text {
                id: text1
                text: "QtRendering ----------"
                font.pixelSize: 20
                anchors.centerIn: parent
            }
        }
        // Myanmar
        Rectangle { width: text1a.width; height:text1a.height
            Text {
                id: text1a
                text: "\u1024 \u1029 \u102a \u104d"
                font.family: fontL_my.name
                font.pixelSize: 54
                anchors.centerIn: parent
            }
        }
        // Khmer
        Rectangle { width: text1b.width; height:text1b.height
            Text {
                id: text1b
                text: "\u1780\u17d2\u1794\u17c0"
                font.family: fontL_km.name
                font.pixelSize: 54
                anchors.centerIn: parent
            }
        }

// NativeRendering ---------------------------------------------------------------------
        Rectangle { width: text2.width; height:text2.height
            Text {
                id: text2
                text: "NativeRendering ----------"
                font.pixelSize: 20
                anchors.centerIn: parent
            }
        }
        // Myanmar
        Rectangle { width: text2a.width; height:text2a.height
            Text {
                id: text2a
                text: "\u1024 \u1029 \u102a \u104d"
                font.family: fontL_my.name
                renderType: Text.NativeRendering
                font.pixelSize: 54
                anchors.centerIn: parent
            }
        }
        // Khmer
        Rectangle { width: text2b.width; height:text2b.height
            Text {
                id: text2b
                text: "\u1780\u17d2\u1794\u17c0"
                font.family: fontL_km.name
                renderType: Text.NativeRendering
                font.pixelSize: 54
                anchors.centerIn: parent
            }
        }
    }
}