Its possible to edit a file in the build-in Jforex editor with the correct filename but have the historical tester use the wrong file.
Additionally you can edit a file loaded from the "edit" button on the historical tester, save and close it, just to see your changes disappear when you reload the strategy.
And a strategy often shows up twice or more in the historical tester strategy drop-down list, depending on how you load the strategy into Jforex.
Furthermore, changing UI controls in the strategy code, don't propagate to what the strategy tester is displaying before you run the strategy twice.

Its all somewhat discouraging.