Micro:bit BLE HID Keyboards more keystroke

Hi - you need to send multiple keys like is shown in the example you linked https://www.espruino.com/BLE+Keyboard

function btnPressed() {
  // Send 'a'
  kb.tap(kb.KEY.A, 0, function() {
    // Followed by capital 'A'
    kb.tap(kb.KEY.N, 0);
  });
}

Sending the keypress takes time - it has to send 'keydown' followed by 'keyup'. It returns immediately and then calls the function in the third argument when finished. You can't just send multiple taps in commands one after the other