I am wondering if this question is on topic or not?
If so, would zazen questions be acceptable even if they have only a tenuous link to martial arts?
Where do we draw the line?
I am generally okay with that question on the site. It is somewhat tenuous to martial arts as you say, but I can see how meditation can be part of one's training.
From my (limited) perspective on martial arts, breathing is especially important in performing techniques. What you are describing I have also done in tai chi. I probably could answer it, but it's not easy. It took me a long time to even just get a basic grasp of what I was doing.
I agree; I don't think the question is better answered by an expert martial artist than by an expert in any other field. I believe the question is off-topic.