Since their personal documents were stolen, how much caution do Bitcoin holders need to follow?
They can pray that this data leak doesn't become a life-threatening attack, as hackers already have their sensitive data, and it could be used against them.
But that's the risk they face due to their government's incompetence in managing such sensitive data. They can take whatever steps they can to improve their security, but that doesn't eliminate the possibility of becoming a target for criminal activity --- and hopefully, that won't happen to them.