I think this is largely due to poor printing technology back in the day. Some of my older books were clearly done on a printing press, so there’s always variation in all of those little details because of each piece used. There’s also the hand-engraving aspect, and when those books are SO large and filled with literally thousands of chants, it’s little wonder that those engravers didn’t have all day to make them perfect.
I’m so grateful you’re doing this.