I experimented a little, and even if you delete every instance of (Delete) and (Fwddel) from the AE shortcuts pref file, the ? still appears,
After copy-pasting it into BBedit, turns out it’s not a real question mark character, but another escaped non-printable character.
I tried different keyboard-layouts, no avail.
In other words: I’m pretty sure it’s a bona fide adobe bug
Is this PC & Mac, anyone ?