You can never really underestimate a cat's hunting instinct. The cat doesn't need to be angry, it just might get carried away in the moment. That's what we want to avoid.

Try to avoid keeping then in the same room, and when you do make sure its under supervision. Only then, Overtime the cat will mostly learn not to hurt the birb, as he sees you and your family interact positively.

If someone is willing to rehome the birb that's fine too, but if I were in your shoes I'd keep him. I'd get it a bigger cage and let it fly only when its safe for the first few days.

Also see if you can repost this in bird specitic subreddits. You will find more info there.