Thanks for playing! The honest answer is, I made this a bit too tricky. The lines don't always clue well. In fact, when I went to play to that point myself, I got stuck on an earlier level...
The best approach I can suggest broadly is to use the check before and after swapping lines to test your individual guesses. Look at anything you think makes sense but might be a little shaky.
But to give more exact hints, I find that it can be hard to figure out the start and end, because they by definition only have one adjacent line as a clue. So I'll rot13 them here, the first line from that screen is:
Yrg zr trg guvf fgenvtug.
And the last one is
Jryy V arire fnvq lbhe obffrf znqr zhpu frafr.
Hope that can help!