This was covered several chapters ago. No, her dying is bad.
Something-something about power collapse within the kingdom... other kingdoms then eyeing the weakened one, and Char's life would still be in danger, as she would be targeted by those opposing kingdoms instead of Giselotte.
The story is the royal birthmark. He has the mark of royalty on his chest. And the rest can all be inferred from the fact he was raised by people who "found" him.