I did not find useful information in Plato. So I look after another way to get information.
to get more precise information and replace qevdevtouch from qt platform plugin with a touch event handler using libevdev.
It seems to get correct info (see log below) since when I'm touching on top left corner I got the correct value. Now I have to filter the message since I got multiple times an equivalent touch message and then pass the touch point info to the main widget.
Spoiler:
Event: time not available, type 1 ( EV_KEY ) code 325 ( BTN_TOOL_FINGER ), value 1
Event: time not available, type 1 ( EV_KEY ) code 330 ( BTN_TOUCH ), value 1
Event: time not available, type 3 ( EV_ABS ) code 57 ( ABS_MT_TRACKING_ID ), value 0
Event: time not available, type 3 ( EV_ABS ) code 59 ( ABS_MT_DISTANCE ), value 0
Event: time not available, type 3 ( EV_ABS ) code 53 ( ABS_MT_POSITION_X ), value 108
Event: time not available, type 3 ( EV_ABS ) code 54 ( ABS_MT_POSITION_Y ), value 88
Event: time not available, type 3 ( EV_ABS ) code 58 ( ABS_MT_PRESSURE ), value 33
Event: time not available, type 3 ( EV_ABS ) code 48 ( ABS_MT_TOUCH_MAJOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 49 ( ABS_MT_TOUCH_MINOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 52 ( ABS_MT_ORIENTATION ), value 0
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, type 3 ( EV_ABS ) code 57 ( ABS_MT_TRACKING_ID ), value 0
Event: time not available, type 3 ( EV_ABS ) code 59 ( ABS_MT_DISTANCE ), value 0
Event: time not available, type 3 ( EV_ABS ) code 53 ( ABS_MT_POSITION_X ), value 108
Event: time not available, type 3 ( EV_ABS ) code 54 ( ABS_MT_POSITION_Y ), value 88
Event: time not available, type 3 ( EV_ABS ) code 58 ( ABS_MT_PRESSURE ), value 33
Event: time not available, type 3 ( EV_ABS ) code 48 ( ABS_MT_TOUCH_MAJOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 49 ( ABS_MT_TOUCH_MINOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 52 ( ABS_MT_ORIENTATION ), value 0
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, type 3 ( EV_ABS ) code 57 ( ABS_MT_TRACKING_ID ), value 0
Event: time not available, type 3 ( EV_ABS ) code 59 ( ABS_MT_DISTANCE ), value 0
Event: time not available, type 3 ( EV_ABS ) code 53 ( ABS_MT_POSITION_X ), value 108
Event: time not available, type 3 ( EV_ABS ) code 54 ( ABS_MT_POSITION_Y ), value 89
Event: time not available, type 3 ( EV_ABS ) code 58 ( ABS_MT_PRESSURE ), value 34
Event: time not available, type 3 ( EV_ABS ) code 48 ( ABS_MT_TOUCH_MAJOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 49 ( ABS_MT_TOUCH_MINOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 52 ( ABS_MT_ORIENTATION ), value 0
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, type 3 ( EV_ABS ) code 57 ( ABS_MT_TRACKING_ID ), value 0
Event: time not available, type 3 ( EV_ABS ) code 59 ( ABS_MT_DISTANCE ), value 0
Event: time not available, type 3 ( EV_ABS ) code 53 ( ABS_MT_POSITION_X ), value 108
Event: time not available, type 3 ( EV_ABS ) code 54 ( ABS_MT_POSITION_Y ), value 90
Event: time not available, type 3 ( EV_ABS ) code 58 ( ABS_MT_PRESSURE ), value 36
Event: time not available, type 3 ( EV_ABS ) code 48 ( ABS_MT_TOUCH_MAJOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 49 ( ABS_MT_TOUCH_MINOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 52 ( ABS_MT_ORIENTATION ), value 0
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, type 3 ( EV_ABS ) code 57 ( ABS_MT_TRACKING_ID ), value 0
Event: time not available, type 3 ( EV_ABS ) code 59 ( ABS_MT_DISTANCE ), value 0
Event: time not available, type 3 ( EV_ABS ) code 53 ( ABS_MT_POSITION_X ), value 108
Event: time not available, type 3 ( EV_ABS ) code 54 ( ABS_MT_POSITION_Y ), value 91
Event: time not available, type 3 ( EV_ABS ) code 58 ( ABS_MT_PRESSURE ), value 37
Event: time not available, type 3 ( EV_ABS ) code 48 ( ABS_MT_TOUCH_MAJOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 49 ( ABS_MT_TOUCH_MINOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 52 ( ABS_MT_ORIENTATION ), value 0
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, type 3 ( EV_ABS ) code 57 ( ABS_MT_TRACKING_ID ), value 0
Event: time not available, type 3 ( EV_ABS ) code 59 ( ABS_MT_DISTANCE ), value 0
Event: time not available, type 3 ( EV_ABS ) code 53 ( ABS_MT_POSITION_X ), value 108
Event: time not available, type 3 ( EV_ABS ) code 54 ( ABS_MT_POSITION_Y ), value 92
Event: time not available, type 3 ( EV_ABS ) code 58 ( ABS_MT_PRESSURE ), value 37
Event: time not available, type 3 ( EV_ABS ) code 48 ( ABS_MT_TOUCH_MAJOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 49 ( ABS_MT_TOUCH_MINOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 52 ( ABS_MT_ORIENTATION ), value 0
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, type 3 ( EV_ABS ) code 57 ( ABS_MT_TRACKING_ID ), value 0
Event: time not available, type 3 ( EV_ABS ) code 59 ( ABS_MT_DISTANCE ), value 0
Event: time not available, type 3 ( EV_ABS ) code 53 ( ABS_MT_POSITION_X ), value 107
Event: time not available, type 3 ( EV_ABS ) code 54 ( ABS_MT_POSITION_Y ), value 92
Event: time not available, type 3 ( EV_ABS ) code 58 ( ABS_MT_PRESSURE ), value 37
Event: time not available, type 3 ( EV_ABS ) code 48 ( ABS_MT_TOUCH_MAJOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 49 ( ABS_MT_TOUCH_MINOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 52 ( ABS_MT_ORIENTATION ), value 0
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, type 3 ( EV_ABS ) code 57 ( ABS_MT_TRACKING_ID ), value 0
Event: time not available, type 3 ( EV_ABS ) code 59 ( ABS_MT_DISTANCE ), value 0
Event: time not available, type 3 ( EV_ABS ) code 53 ( ABS_MT_POSITION_X ), value 107
Event: time not available, type 3 ( EV_ABS ) code 54 ( ABS_MT_POSITION_Y ), value 93
Event: time not available, type 3 ( EV_ABS ) code 58 ( ABS_MT_PRESSURE ), value 38
Event: time not available, type 3 ( EV_ABS ) code 48 ( ABS_MT_TOUCH_MAJOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 49 ( ABS_MT_TOUCH_MINOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 52 ( ABS_MT_ORIENTATION ), value 0
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, type 3 ( EV_ABS ) code 57 ( ABS_MT_TRACKING_ID ), value 0
Event: time not available, type 3 ( EV_ABS ) code 59 ( ABS_MT_DISTANCE ), value 0
Event: time not available, type 3 ( EV_ABS ) code 53 ( ABS_MT_POSITION_X ), value 106
Event: time not available, type 3 ( EV_ABS ) code 54 ( ABS_MT_POSITION_Y ), value 93
Event: time not available, type 3 ( EV_ABS ) code 58 ( ABS_MT_PRESSURE ), value 38
Event: time not available, type 3 ( EV_ABS ) code 48 ( ABS_MT_TOUCH_MAJOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 49 ( ABS_MT_TOUCH_MINOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 52 ( ABS_MT_ORIENTATION ), value 0
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, type 1 ( EV_KEY ) code 330 ( BTN_TOUCH ), value 0
Event: time not available, type 1 ( EV_KEY ) code 325 ( BTN_TOOL_FINGER ), value 0
Event: time not available, ++++++++++++++++++++ EV_SYN
Event: time not available, type 1 ( EV_KEY ) code 325 ( BTN_TOOL_FINGER ), value 1
Event: time not available, type 1 ( EV_KEY ) code 330 ( BTN_TOUCH ), value 1
Event: time not available, type 3 ( EV_ABS ) code 57 ( ABS_MT_TRACKING_ID ), value 0
Event: time not available, type 3 ( EV_ABS ) code 59 ( ABS_MT_DISTANCE ), value 0
Event: time not available, type 3 ( EV_ABS ) code 53 ( ABS_MT_POSITION_X ), value 1619
Event: time not available, type 3 ( EV_ABS ) code 54 ( ABS_MT_POSITION_Y ), value 83
Event: time not available, type 3 ( EV_ABS ) code 58 ( ABS_MT_PRESSURE ), value 20
Event: time not available, type 3 ( EV_ABS ) code 48 ( ABS_MT_TOUCH_MAJOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 49 ( ABS_MT_TOUCH_MINOR ), value 0
Event: time not available, type 3 ( EV_ABS ) code 52 ( ABS_MT_ORIENTATION ), value 0
Event: time not available, ++++++++++++++++++++ EV_SYN