Well, that's why it's called title safe. There is no guarantees that your content will be readable outside that area. It may be visible, but parts of it may get cut off. Though, to let truth have its way, even the cheapest, most atrocious TV these days is a lot better then the tubes when title safe was really critical. So it's usually okay to move slightly outside the title safe box (about one third more), but definitely stay within the action safe. It also depends for what kind of TV station you work. Big stations have dedicated quality assurance and archival procedures that are quite rigid and do not allow to deviate, or else your stuff won't be aired. Smaller local stations are less picky.
you need to keep it inside caption safe. it could well be rejected if it's outside.
also be aware there are a lot of different caption safes. in the UK you need to keep it in 14:9 caption safe to be broadcast.
this is overkill as any 16:9 monitors and most 4:3 can cope with more than this, but the rules haven't changed since 14:9 came in.
if media comes in outside of this it will be rejected at channel 4 where i work. very occassionally media gets exempt from this if it cannot be remade or fixed in house. it will then have to be broadcast 16:9.
i'd ask for the spec from the client/broadcaster and keep within that..
captions can go outside if they're moving, for instance: large caption growing to fill screen. this is where it gets subjective, but they obviously need to be inside caption safe for a reasonable time.