Google-sheets – Google Sheet Humongous Bottleneck Caused by this FILTER function. How to fix

If I interpreted your question right you want your script run only if you edit a cell in one of the three sheets you mentioned.

You can use getName() on actSht to get the name of the sheet in which you have edited a cell. The you can just use an IF-statement to check if it's one of your sheets.

Here's an example of what I described above:

function onEdit(e) {
  var sheet = SpreadsheetApp.getActiveSheet();
  if (sheet.getName() == "Project" || sheet.getName() == "Tasks"){
    //Some code that only runs if the cell edited is in a sheet named "Projects" or "Tasks"
  }
}

And here's how you can apply it to your code:

function onEdit(event)
 {
    var ss = SpreadsheetApp.getActiveSpreadsheet();
    var actSht = event.source.getActiveSheet();
    if(actSht.getName() == "Active Tickets" || actSht.getName() == "Closed Tickets" || actSht.getName() == "Pipeline"){

        var actRng = event.source.getActiveRange();

        var index = actRng.getRowIndex();
        var dateCol = actSht.getLastColumn();
        var lastCell = actSht.getRange(index,dateCol);
        var date = Utilities.formatDate(new Date(), "GMT-3", "dd/MM/yyyy HH:mm");

        lastCell.setValue(date);
        lastCell.setComment("Ultima Modificacion: " + actRng.getA1Notation() +' por     '+Session.getActiveUser());
        ss.toast('Ultima Modificacion = '+ actRng.getA1Notation()+' por   '+Session.getActiveUser());
    }
}

You added single quotes to the sheet references:

=ListBy('sheet1'!A1:A10, 'sheet1'!A1:A10, "needle")

If you leave those:

=ListBy(Sheet1!A1:A10, Sheet1!A1:A10, "needle")

then your script works as planned.

Screenshot

Sheet2:

Sheet1: