Cannot Get/Set Parameters Outside ParameterEditor.qml in QGC

Hi developers,
I want a modification in the QGC, especially for adding TextFields to get and set WP_RADIUS and LOIT_RADIUS parameters directly in PlanView.qml.
However, I have stucked for a few days. When, I get a Fact related to the parameter name in PlanView.qml, the value is always zero and I cannot set the parameter’s value.

Here is the code that I have added.

I defined the controller like this in the PlanView.qml:

        ParameterEditorController {
            id: controller;

And I did a testing to get and set AHRS_TRIM_Y parameter in a TextField inside PlanView.qml like this:

        id:     atextfield
        onEditingFinished: {
                  var fact = controller.parameters.get(1)
                  fact.value = "5"

When I edit the TextField, the output in the console is false. The value is zero. It should be 5 as in APM:

   qml: Fact(<a hex number>)
   qml: AHRS_TRIM_Y
   qml: 0

But, when I did the same testing in ParameterEditor.qml, the output is true (equal to value in APM):

   qml: Fact(<a hex number>)
   qml: AHRS_TRIM_Y
   qml: 5

What makes this different?
Is it possible to get and set the parameters outside the ParameterEditor.qml?
Is there any technique that should be used to do this?

I am so sorry if this is a dummy question.
I would appreciate any help in this matter.

@DonLakeFlyer Hi, it seems that you are an expert. Would you kindly help me for this problem? Thanks.