How about the follwing solution to conclude this discussion: You use a script function that modulates your profits with the exchange rate.

I can not recommend this, for several reasons. For instance it adds a level of overfitting to the simulation and reduces the quality of trained parameters. So your strategy will probably become less profitable. But if you want to do that nevertheless, I can post a short function here that replaces the broker's pip cost with an exchange rate that you can select. Would that work for you?