Touch event handling in custom QQuickItem

Reproducer attached. The goal is to have the custom QQuickItem capture touch events, iterate and log everything it captures. Basically what a MultiPointTouchArea is perfectly capable of, but the original reporter would like to use this custom QQuickItem.

And some problems observed when the button is tapped on:
1. Tap it with only 1 finger, then only Pressed event is logged, e.g.

# of points: 1
Point # 0 id 22
QEventPoint::Pressed : 0 QEventPoint::Pressed

The Release event is missing.
2. Tap it with 2 fingers, the result can be various. Since it is very hard to land both fingers at the same timing, then you may get 1 Pressed + 2 Release or 2 Pressed + 1 Release. This is the log of the latter:

# of points: 1
Point # 0 id 23
QEventPoint::Pressed : 0 QEventPoint::Pressed
# of points: 2
Point # 0 id 24
QEventPoint::Pressed : 0 QEventPoint::Pressed
Point # 1 id 23
default
# of points: 2
Point # 0 id 24
default
# of points: 1
Point # 0 id 24
QEventPoint::Released : 0 QEventPoint::Released

Touch point 23 is pressed but not released.

Either case, it is different from what, e.g. libinput debug-events, reports. The number of Pressed event should equal the number of Release event as well as the number of taps. For example, this is what libinput shows for 1 tap:

 event6   TOUCH_DOWN              +15.877s	0 (0) 63.50/45.72 (225.18/99.45mm)
 event6   TOUCH_FRAME             +15.877s	
 event6   TOUCH_UP                +15.907s	0 (0)
 event6   TOUCH_FRAME             +15.907s

You can clearly see 1 DOWN + 1 UP and that is consistent and always the case.

I am not sure if it is because missing logics in custom QQuickItem or there are some disconnections in Qt code. If it's the former, maybe it's better to put some notes in documentation?