I love that you do further analysis on the MACD, however my understanding is that the MACD line (blue) is calculated as the 12ema minus the 26ema, and the red/orange line is the 9ema of the MACD line. Splitting hairs aside, your interpretation remains valid. So for example, a cross of the 12/26 EMAs occurs when the MACD (blue) crosses the zero line. Hope this helps!