Wrong inputs!! the MACD Histogram in Ctrader turns Macd line into columns and thats not a MACD histogram:
MACD Histogram= MACD line - Signal line
therefor: the Impulse system here is taking the wrong inputs which is the MACD line instead of the MACD Histogram. and this will lead to a late signal. 
Any way, there's another indicator in ctrader that gives the right inputs which is (MACD crossover).