Please note that this Expert Advisor (EA) is not a trading EA. It just creates pending orders at a specified time. If the market price matches the pending orders created by it then they get executed. So, I do not know whether using strategy testing would be of any use for this EA.
Regarding the stop loss parameter, the broker requires that there be a certain pip distance maintained between the pending order created and it stop loss. Sometimes if the melodica system strategy makes creates a pending order that conflicts with this broker requirement then the pending order is not created. So, a manual pending order can be created using the values alerted by the EA or giving a stoploss input to the EA that will not conflict with the broker requirements. Also, a 70 pip stoploss was something thrustidle74 said in one of the post that made good profit. So, the system can be tried with a fixed stoploss using this parameter. But then, this is only a pending order creating EA and not a trading EA.
Hope this information helps.