Those 3 pairs was risky for me. For you may be not.
For my deposit size.
because ... just imagine that you attach EA to GBPJPY.
EA opened sell by 0.1 lot size. If you have more than -10 pips in this open order so EA will open the other order by 0.2 lot size. Price of the first order moved in the wrong direction and you see -20 pips - EA will opened 3rd order by 0.4 lot size.
-40 pips - 0.8 lot size.
-50 pips - 1.6
-60 pips - 3.2.
And 2 times like that (2 rounds).
and so on.
So 3.2 lot size is coming very very easy even in flat market for GBPJPY, GBPCHF and CADJPY for example. Because EA is operating on close bar and H1 timeframe.

May be I will try to use M15 timeframe? Or use shift = 0?

Of course if you have real deposit 50,000 and will trade by 0.01 size it may be fine for you.
But I want to trade by 0.1 lot size so 3.2 lot is too much for me already.
That is why I said that those pairs are too risky for me and I decided to use maximum orders = 5.

It is possible to backtest this EA. Because EA was coded very good and on close bar. So, backtesting is reliable for this EA.