jsfl to be fixed

If you need to process all the elements, then this can be done by the timeline object of each character individually. You can get this object from the library element

// Loop through all elements on the stage
var doc = fl.getDocumentDOM();
var items = doc.library.items


for (var n = 0; n < items.length; n++) {
	var item = doc.library.items[n]
	if (item.itemType === "movie clip" || item.itemType === "graphic" || item.itemType === "button") {
		var timeline = item.timeline
		for (var i = 0; i < timeline.layers.length; i++) {
			var layer = timeline.layers[i];
			for (var j = 0; j < layer.frames.length; j++) {
				var frame = layer.frames[j];
				var elements = frame.elements;
				for (var k = 0; k < elements.length; k++) {
					var element = elements[k];

					// Check if the element is a symbol
					if (element.elementType === "instance") {
						// Adjust properties of the symbol
						element.symbolType = "graphic";
						// Additional property adjustments can be made here

					}
				}
			}
		}
	}
}

// Loop through all the objects in the current FLA
var doc = fl.getDocumentDOM();
var sel = doc.selection;
var numItems = sel.length;
for (var i = 0; i < numItems; i++) {
  var item = sel[i];
  if (item.itemType === "movie clip") {
    // Convert movie clip to graphic symbol
    item.convertToSymbol("graphic");
    // Access the newly converted graphic symbol
    var graphicSymbol = doc.library.findItemIndex(item.name);
    // Set the properties of the graphic symbol
    doc.library.items[graphicSymbol].setIsLooping(false); // Example property, replace with the desired property
  }
}

Use jsfl to adjust movie clip properties of all objects to graphic symbols