What happens to the onions and peppers that have cooked in the broth for 4 1/2 hours? Are they too wilted/tired to serve with the other veggies?

To me, the veggies used in stews and cornbeef etc are sacrificial elements.

Potatoes, fresh carrots, cabbage are added at the last hour or so they retain some integrity.
The ones in the broth can be blended with the liquid for gravy. The onions I remove because they still have some shape and good sugars from the low/slow cooking.

They're pretty deflated by the end, but taste them and see what you think!