do I have to fix a cracked engine cradle

It's not uncommon in those Buicks or for that matter General Motors products in general that the subframes suffer from rotting issues and typically crack where the steering rack is mounted. In regards to a safety issue if the subframe decides to crack completely there is a great possibility that you could lose control of steering and injure yourself or another. Fortunately those sub frames a very reasonable to buy used. So I would advise you to contact a repair shop and make arrangements to get a profesional eval. Kagan's Auto Service (Brian Kagan) Phone # 1(781)-284-9564. Email: kagansservicestation@gmail.com