Language works when we think the same, connecting the words to the same meanings and such. But that never actually happens 100%. It might be closer to 80%. (or if it’s a strange subject, 15%)
So this “conversation” that we’re having here is, to some degree, not actually happening.
But we pretend that it is.
So how much are we pretending? How much of the conversation is hallucinatory conversation?
I think it would depend on our previous interactions.  Think of texting. When you barely know someone and you text them, it’s usually straight forward ’who, what, when, where, how’ sorts of info. But when you text an old friend you may allude to old inside jokes or other ’insider’ references that would be ambiguous to a stranger. You ‘hallucinate’ to fill in the meaning from previous context.
Thus a text from a good friend entails more ‘hallucination’ than a text from a new work colleague.