transposedown.qml

import QtQuick 2.0
import MuseScore 3.0

MuseScore {
  menuPath: "Plugins.transposeDown"
  onRun: {
    for (var i = 1; i-- > 0;) {
      cmd("transpose-down");
    }
    Qt.quit();
  }
}

transposedown2.qml

import QtQuick 2.0
import MuseScore 3.0

MuseScore {
  menuPath: "Plugins.transposeDown1"
  onRun: {
    for (var i = 2; i-- > 0;) {
      cmd("transpose-down");
    }
    Qt.quit();
  }
}