What happens if someone gets access to the email address you used to setup deltachat? Can the private keys be compromised or would they explicity need to regenerate a key? If so, would it be noticeable that someone has hacked your Delta client?
The private key stays on your device, the email account password does not suffice to find it out.
That’s why there is the “Changed setup for firstname.lastname@example.org” message. So you will notice that the key has changed and if you are suspicious you can ask that person about it.