Based on the spoiler information from the latest preview of Exodus, and specifically based on the Revised Execution Rules (and incidentally on the Revised Loyalty Deck), here is a brand new idea for balancing Cain:
Leave Cain's text alone.
But, at the beginning of the game, put her aside. She cannot be chosen.
When a human is Executed, you may choose Cain as normal, amongst all of your other choices of replacement character.
Simple as that; of course, it might lead to a whole category of "set aside at the beginning of the game" characters. But since the replacement for an executed character now gets a Loyalty Card, it's plausible.
Like I said, this might be moot because of other rules in Exodus that we haven't seen yet, or (less likely) this might actually be the rule.
(And of course, it wouldn't easily apply to our actual pre-Exodus-release game, but it is an idea set aside for the future)
What do you think about these particular apples?