DroH1

function _onEdit(e) {    
    let sheet = e.source.getActiveSheet();
    let address = e.range.getA1Notation().toUpperCase();
    let row = e.range.getRow();
    let col = e.range.getColumn();
    let newValue =  e.value;
    let oldValue =  e.oldValue;

    if ((["1"].includes(sheet.getName())) && (col===26) && (newValue==="Обработано")) {
        sheet.getRange(row, 26-2).setValue(new Date());
    };
};