I have been toying with some events, and notice that there are two different ways to remove 'leaders' (amongst other units) in the event files.
One...
RemoveUnit
Removes the named unit in question, but also any other unit attached (i.e., if you remove a general, you also remove all of their subordinate attached forces in his division).
Two...
RemoveCuSubUnit
Removes the named unit in question, but, leaves everything else (tried this with an army HQ, and it removed the commander, but left the HQ!).
Now, there were some problems in some events before that had a leader removed, and so too were all of their brigades (if in a division). These events were 'blocked' from the game. However, they all use the "RemoveUnit" command instead of "RemoveCuSubUnit" command.
I figure that these events would actually work as designed, if the tags were changed to the correct designation (leave the brigades, remove the leader).
Therefore, those historic deaths via natural causes, jelous husbands, etc., could possibly be re-integrated.