I'm with a team with a marker error, (which I also have in my own project:)
We want to use the \mr marker to mark out \mr (Kʊjʊʊ́ 10.11 - 21.35)
This is referring to the current book rather than another book, so using the actual book name would seem strange. I asked the team why they thought it was necessary, and they said it is a help to new readers, rather than just to have \mr (10.11 - 21.35)
Kʊjʊʊ́ is the word for chapter, rather than a book name, so PT rejects this as a scripture reference error.