Adlet ran away because Nacchie would have pawned him if he stayed. Hans didn't reply to his call, so he wasn't there. If he did as you said, he'd already be dead.
It was specifically mentioned that Chamot could somehow sense dead bodies even if they were buried underground. That meant she could more or less sniff out bodies anywhere within the barrier. That's why they hid it inside a corpse, because the smell of death masked the other.
I completely agree with more foreshadowing, but the logic behind the reveal itself was sound, albeit sudden.
EDIT:
Forgot to mention the most important thing.
Flamie = waifu of the year.
Got a boner each time she called Adlet's name, her voice bleeding with concern.