Hi Boyan,
Sometimes an EA will work on a different pair and sometimes not. So it is hard to say if the EA in question contributed to some of the loss without doing further analysis. The way I would check to see if the EA contributed to the loss would be to do a backtest of the EA on both pairs. Then you can look at the results of both backtests to see if the EA contributed to some of the loss when attached to the wrong pair. You can use the MetaTrader Strategy Tester to do the backtest but EA Studio would give a more accurate backtest.
Also, now that I think about it more, you can do a backtest on the 5 EAs for the last one month and then look at the resulting graph to see if the EAs are in a nice upward profitable trend. This would give you an idea if the EAs are being profitable over the longer term and that they are just going through a short term drawdown.
Alan,