Make Time Stretch visible

Here you go, Make sure to test it enough before trusting the results
The first one works on all project comps, and the second works on project panel selected comps only.

function getStretch(layer) {
    var s = layer.stretch;
    if (s !== 100) {
        s = s.toFixed (1);
        // Create a new marker
        var marker = new MarkerValue("Stretch "+ s);
        // Add the marker at Layer in point
        layer.property("Marker").setValueAtTime(layer.inPoint, marker);
    }
}
app.beginUndoGroup("Label Time Stretched Layers");
for (var i = 1; i <= app.project.numItems; i++){
    if (app.project.item(i) instanceof CompItem){
        for (var j = 1; j <= app.project.item(i).numLayers; j++){
            var layer =  app.project.item(i).layer(j);
            getStretch(layer);
        }
    }
}
app.endUndoGroup();

function getStretch(layer) {
    var s = layer.stretch;
    if (s !== 100) {
        s = s.toFixed (1);
        // Create a new marker
        var marker = new MarkerValue("Stretch "+ s);
        // Add the marker at Layer in point
        layer.property("Marker").setValueAtTime(layer.inPoint, marker);
    }
}
//
app.beginUndoGroup("Label Time Stretched Layers");

var selectedItems = app.project.selection;
for (var i = 0; i < selectedItems.length; i++) {
    var comp = selectedItems[i];
    if (comp instanceof CompItem) {
        for (var j = 1; j <= comp.numLayers; j++){
            var layer =  comp.layer(j);
            getStretch(layer);
            }
        }
    }
app.endUndoGroup();