I know you weren't asking me, but ...
Because it's almost unimaginable that an automated trailing stop can be a sensible, long-term exit-strategy for any forex method/system.
Trailing the stop manually above/below a recent high/low will inevitably be far superior, overall.
Trailing stops sound attractive and appealing, but that thinking fails (among other things) to take account of all the times that a trade moves in the right direction, then has a brief retracement - just enough to hit the trailed stop - before proceeding on its merry way, as you wanted/expected but having closed out your trade just before the big move. In other words, it’s a good way to get the overall direction right and still not make (much) profit.
It's "amateur nonsense" that forex counterparty market-makers who are trading against their forex customers love people to use. Intractive Brokers not so much, because they're a genuine broker, executing forex trades in the underlying market on their clients' behalf, and they have no incentive for their traders to lose.