I think that any set of symbols in any form, capable of reconstructing the requisite experience of reality allows for some degree of truth communication between humans, superhumans, human-made-machines, and if they exist, aliens capable of action and communication.
I have a hard time imagining that a basic instruction set is not accessible to any sentient creature capable of acting in reality. That’s because most of what we wish to communicate is state change, and I can easily see a universal grammar of state change in the physical world, just as easily as I can see a universal grammar of mathematical operations. Actions produce state changes.
What I can’t see is a universal grammar of subjective experience. It is hard enough to communicate across cultures and languages. I can see “in my interests” and “against my interests” as well as the plural “our interests”. It appears to be possible to create a universal grammar of emotion among earth’s creatures, because it is a very simple thing. So maybe a universal grammar is possible (now that I think about it, I think I might be able to do it.)
(Damn…. I just gave myself more work to do.)