Here is how I interpret your claim here: The only way the Copenhagen interpretation could be an absolute state theory - i.e. a theory where the quantum state of a system is absolute, not relative to some other system - is for collapse to be caused by conscious agents. Am I misinterpreting you?

You got it! Thank you!

If I'm not, I don't see why you believe this. The Copenhagen interpretation does say that a certain class of interactions - measurement interactions - produce collapse. And I acknowledge that it cannot maintain that all physical interactions are measurement interactions. That view has been conclusively refuted empirically. However, why think that the only alternative is that measurement interactions must involve conscious observation? Bohr, as far as I can tell from his mysterious proclamations on the topic, seemed to think that any interaction with a macroscopic system is a measurement interaction.

There might be some other type of measurement, not involving consciousness, that would occur rarely enough to work. I'm just not aware of any.