I was also thinking about what you were saying about the voices at the end getting muddy.
This was not a mixing issue, but a singing issue. I added that spot at the last minute, so I was still acclimatizing to how I was going to go about pronouncing the old Norse. It's actually recorded on the same tracks that the earlier stuff is recorded on. It's 100% singing not in unison, singing off key, which is why it gets better at the other tracks when the sound gets clearer.