Selection Fill In Script Question

I'm having trouble understanding. I thought the tolerance for selection only affects which pixels are selected and not how the pixels are colored. How does the tolerance for magic wand affect the coloring? 

As for the inconsistency of the pixels to contract, I'm sorry about that. I have to change the number manually from 4, 8, and 12 each time. Sorry for that inconsistency in the question.

I'm am using Photoshop 21.2.4 with the following script and image.

/ (c) Copyright 2005.  Adobe Systems, Incorporated.  All rights reserved.

/*
@@@BUILDINFO@@@ Welcome.jsx 1.0.0.1
*/

var begDesc = "$$$/JavaScripts/Welcome/Description=Show a simple alert when Photoshop starts." // endDesc
var begName = "$$$/JavaScripts/Welcome/MenuName=Welcome" // endName

// on localized builds we pull the $$$/Strings from a .dat file, see documentation for more details
$.localize = true;




try {
 //Colors used in the script
//  Light Blue          78CAF1
//  Dark Blue           0000FF
//  Light Green         A5F1AC
//  Dark Green          006F00
var CustomerColorArray = ["78CAF1","A5F1AC"];
var WhizColorArray = ["0000FF","006F00"];

// Define the x and y coordinates for the pixel in the top left cornor
var Left = 0;
var Right = 1;
var Top = 0;
var Bottom = 1;

if(documents.length){

//Setup Counter to loop through pre-set colors

for (var counter = 0 ; counter <= 1; counter++){        
        //  Identify color to look for
        var selectColor = new SolidColor();
        selectColor.rgb.hexValue = CustomerColorArray[counter];
        
        // Identify color to fill in
        var fillColor = new SolidColor();
        fillColor.rgb.hexValue = WhizColorArray[counter];

        //  Fill in a temporary Pixel with select color
        activeDocument.selection.select([[Left,Top],[Right,Top],[Right,Bottom],[Left,Bottom]], SelectionType.REPLACE, 0, false);
        activeDocument.selection.fill(selectColor);
        activeDocument.selection.deselect();
    
        // Use magic want to find all pixels with select color
        magicWand (Left, Top, 30, false, false, false);

        //Contract the selection by x number of pixels, which is equivilent to distance away from objects
        activeDocument.selection.contract(new UnitValue (8, "px"))
        
        //Color the selection as the vacuumable color
        activeDocument.selection.fill(fillColor);
        activeDocument.selection.deselect();
        
        }
}
alert( localize( "$$$/JavaScripts/Welcome=Coloring Complete" ) );
 
function magicWand(x,y,t,a,c,s) {
    if(arguments.length < 2) return;// make sure have x,y
    if(undefined == t) var t = 32;// set defaults of optional arguments
    if(undefined == a) var a = true;
    if(undefined == c) var c = false;
     if(undefined == s) var s = false;
    var desc = new ActionDescriptor();
        var ref = new ActionReference();
        ref.putProperty( charIDToTypeID('Chnl'), charIDToTypeID('fsel') );
    desc.putReference( charIDToTypeID('null'), ref );
        var positionDesc = new ActionDescriptor();
        positionDesc.putUnitDouble( charIDToTypeID('Hrzn'), charIDToTypeID('#Rlt'), x );// in pixels
        positionDesc.putUnitDouble( charIDToTypeID('Vrtc'), charIDToTypeID('#Rlt'), y );
    desc.putObject( charIDToTypeID('T   '), charIDToTypeID('Pnt '), positionDesc );
    desc.putInteger( charIDToTypeID('Tlrn'), t);// tolerance
    desc.putBoolean( charIDToTypeID('Mrgd'), s );// sample all layers
    if(!c) desc.putBoolean( charIDToTypeID( "Cntg" ), false );//  contiguous
    desc.putBoolean( charIDToTypeID('AntA'), a );// anti-alias
    executeAction( charIDToTypeID('setd'), desc, DialogModes.NO );
};
}


catch( e ) {
	// always wrap your script with try/catch blocks so you don't stop production
	// remove comments below to see error for debugging 
	// alert( e );
}

I'm using a script to select a specific color with tolerance = 0 and then contracting the selection by 3 pixels

        // Use magic want to find all pixels with select color
        magicWand (Left, Top, 30, false, false, false);

        //Contract the selection by x number of pixels, which is equivilent to distance away from objects
        activeDocument.selection.contract(new UnitValue (8, "px"))
        
        //Color the selection as the Whiz vacuumable color
        activeDocument.selection.fill(fillColor);
        activeDocument.selection.deselect();