If I want to change the text on certain pages generated by the Peer-to-Peer add-on, it's currently not possible.

The method for changing text (when that text is not editable in the user interface) is to use WordPress translation tools.

The Peer-to-Peer add-on currently doesn't surface all of the "strings" that should be translatable in the translation file (POT). One example is the Register Screen pictured below.

That means I can't translate that screen to a different language, and I can't modify that text via PHP snippet if I want to.