Setting Opacity and Feathering of a selected Brush via script

Hi all - I am working on a script that relies on some preloaded brushes. From what I can gather (I'm traditionally an InDesign scripter), the only way to set opacity is through a preloaded brush. I do have a function in script that checks the brushes, where I'd like to set the opacity and feather weight of these brushes if they exist. I can't figure out how to Action Script it. Does anyone have any guidance? TIA. 

var hasBrushes = function(weight) {
  
  function checkStroked(enabled) {
    if (enabled != undefined && !enabled)
      return;
    var desc1 = new ActionDescriptor();
    var ref1 = new ActionReference();
    ref1.putName(cTID('Brsh'), "Solid" + weight.toString() + "px"); 
    desc1.putReference(cTID('null'), ref1);
    executeAction(cTID('slct'), desc1, DialogModes.NO);
  };

  
  function checkDotted(enabled) {
    if (enabled != undefined && !enabled)
      return;
    var desc1 = new ActionDescriptor();
    var ref1 = new ActionReference();
    ref1.putName(cTID('Brsh'), "Dotted" + weight.toString() + "px");
    desc1.putReference(cTID('null'), ref1);
    executeAction(cTID('slct'), desc1, DialogModes.NO);
  };

  try {
     checkStroked();
     checkDotted();
  catch(e) { return false; }
  return true;
}