If they know modern languages and the world situation, then they’ve been observing things all along somehow. Perhaps through the eyes and ears of housecats.
If they don’t, then you’ve got an awful lot to teach them. In the meantime, they’d probably act like they were assuming they were in some phase of their afterlife mythology, but one where no one could speak their language… well, I suppose if you could pull this off, you’d be smart enough to bring along some scholars who think they can speak Ancient Egyptian of the appropriate era… I wonder what the state of