A substrate of some kind is assumed.

But is it? This is something that I simply have to question. In fact, if I have any religion whatsoever, it's probably my refusal to concede that it works that way, :) -that there is anything that is not bootstrapped. I think that instead of defining existence, we should simply see if we can define context, and then the boundaries of context. It's my gut feeling that in the nature of these boundaries, we have answers to our question.

reality as a text that is read by a reader.

This is also the seed of the many worlds interpretation, IMO. But, not simply just that. Although I dislike the 'many worlds' interpretation, I don't disagree with the motivation behind it. I guess this might be why (off the cuff here):

Cognition is a context. Instead of delineating between the pattern and the perceived, maybe there is more fruit to be found looking at the nature of that context as it relates to others. What are the boundaries of a cognitive scenario? Rather than define it from within, maybe we can define it from without.

In that sense, yes cognition is a reflection. But, if we are to compare it to other reflections that we don't consider to be cognitive scenarios, we'd find that the cognitive reflection is always incomplete. Maybe cognition isn't something remarkably greater than, but something remarkably less than. Maybe cognition is the gift of imperfect reflection? And what is gained by that imperfection, is space that must be filled. And what is it filled with? -The only thing available, other imperfect reflections. This is something that feels unique and free to me.