I didn't try putting a sample together to test that everything is working as it should but I do see a problem with your code. A ValueInput object is used when you first create a ValueInput object but after that you access the value of the input using either the expression or value properties. Using a ValueInput lets you use either a string or a double to set the initial value of the input. If a string is used it is evaluated using the current document units and any units within the string. If a double is used then it is treated as database units. For example, for lengths it will always be centimeters. However the result in the dialog will be displayed in the current document units.
One the command input has been created you can get and set it's value using the expression property (which requires a string and is evaluated using document units) or the value property (which is a double and will be in database units). Which one to use depends on which is the most convenient for you and typically depends on where the data comes from. For example, if you're reading if from a file or from some user entered data then it a string is typically more convenient. If it's a value you've calculate then a double is better.
Here's a small section of your code:
if(getFixture == 'D051251WM') {
DoveLengthInput = initialVal10;
DoveWidthInput = initialVal11;
}
Try changing it to this and see if it solves the problem:
if(getFixture == 'D051251WM') {
DoveLengthInput.value = 1.475;
DoveWidthInput.value = 0.7;
}
I also don't see in your code where you're setting DoveLengthInput and DoveWidthInput. You can get them doing something like the following:
DoveLengthInput = inputs.itemById('WhateverIDYouUsedWhenCreatingIt');