Thanks for catching that! Given the MODIFIER you're describing, I assume this is the COURT, rather than the CHAPEL?
The intent is indeed for the HORDS to stop SPAWNING after the final "original" ENEMY is killed, but reading it this long after I wrote it, it does seem poorly explained and I apologize for this. I am actually a little surprised this wasn't caught by myself earlier, or during playtesting by others.
Something always falls through in a book this size, unfortunately. I've updated the book with clarification, there! It now reads "once the original ENEMIES are dead" instead of "all ENEMIES". You can redownload the PDF to find that resolved.