Illustrator script that will convert all SPOT colors to Process (CMYK)

Based on the topic https://community.adobe.com/t5/illustrator-discussions/how-to-change-spot-color-to-process-cmyk-by-disabling-global-option/m-p/3345667 with improvements. You can set the name suffix in the variable. We cannot change the Color Type directly, but we can create a new Process color with values from Spot, and then delete Spot.

//@target illustrator
main();

function main() {
  var suffix = '_CMYK';
  var isRmvSpot = true; // true of false

  var doc = app.activeDocument;
  var len = doc.spots.length;
  var isRgb = /rgb/i.test(doc.documentColorSpace);

  for (var i = 0; i <= len - 1; i++) {
    if (doc.spots[i].colorType === ColorModel.REGISTRATION) continue;
    var spotName = doc.spots[i].name;
    var spotValue = doc.spots[i].getInternalColor();
    var sw = doc.swatches.add();
    sw.name = spotName + suffix;
    var newColor = setColor(spotValue, isRgb);
    sw.color = newColor;
  }

  if (isRmvSpot && len > 0) doc.spots.removeAll();
}

function setColor(arr, isRgb) {
  var color = isRgb ? new RGBColor() : new CMYKColor();
  if (isRgb) {
    color.red = arr[0];
    color.green = arr[1];
    color.blue = arr[2];
  } else {
    color.cyan = arr[0];
    color.magenta = arr[1];
    color.yellow = arr[2];
    color.black = arr[3];
  }
  return color;
}