So, I'm going to drop some premises here:
First, Birdboi, if it was clever (which it seems to have been) would not say anything that would be verifiable as a lie-of-fact. (As opposed to lies-of-presentation, where the lie is in what it
doesn't say. Those are its stock in trade.) I presume this because if this is not the case, then anyone who isn't already desperate/hooked would go "you're a liar, go away, your promises are worthless." So, anything it outright states is true, if probably misleading.
Second, Chaos is not omnipotent/infallible. We're probably up against a functional Intrigue score at least as high as Mathilde's, probably higher... but not enough higher to make her auto-lose.
So, I conclude that it is
possible to get some useful information out of what Birdboi said, even if it did its best to make it very very hard, by virtue of putting most of what it said in the terms of "from a certain point of view"/Jedi-lies.
DragonParadox confirmed as Tzeentch!
Mathilde can be up-front about "a minion of the Plotter talked at me after a miscast, doing the necessary check-in per Procedure", without disclosing everything it said. (I presume)
The Chaos Gods are not omnipotent. They can be beaten. Even by mortals.
The defining characteristic of paranoia is the
inability to accurate determine what is not a threat.
Again, this is not a sure thing. The Chaos Gods are powerful, sure, but not infallible. We might lose a particular exchange, but that doesn't imply more than that.