As I 'm a lazy, lazy person, and a cheapskate, I'd be inclined to just bend the boom fitting to its original shape (probably best done after removing it temporarily from the boom). Straight-enough is probably good enough - it's an admirably low-tech joint.
Re the gouge in the mast, I'd just fill it with a little epoxy (if I could be bothered), or some putty, and a couple of coats of varnish. Check that the eye-screw is stil solidly-screwed into the mast. If not, unscrew it, fill the hole with an epoxy (or tightbond etc) soaked dowel plug, and re-drill a hole for the eye-screw, when its all dry.
As to what happened, my guess is that at some point in the trip, someone let go the sheet, and the boom was pushed by the wind too far around forward of the mast, putting enough leverage pressure in the joint fittings to mangle them.
Probably worth considering easing your sheet out (easiest and safest done while still on land), until the joint starts to protest (probably somewhere around the point where the boom is perpendicular to the boat's keeline, and then put a knot in the sheet behind the last pully/block so that, even if the sheet is let go again, the knot will stop the boom from swinging so far around forward again.
But, be careful if you do knot the sheet. Sometimes being able to completely let-fly a sheet, even at the expense of a bent goosneck, could save you from a capsize. Wit a little experience, it will be second-nature to always tend the sheet in sympathy with the limits of the rig.
With all that said, I agree that Old Yeller's suggestion of jaws and a parrel would, although possibly a little more work, would allow 180 degree rotation of the boom with no damage.
Though, to work smoothly, you'd also need to somehow incorporate a round section into the mast where it meets the jaws, as the current square section could bind (or be too sloppy).
Also, one of the big advantages of the sprit rig is that, once the sheet and snotter (love that word!) are let go, the whole kit can be simply folded on the mast with all the spars and sail in place for the next outing.
For that to happen, the boom needs to be able to fold vertically up against the mast. While the jaw/parrel arrangement certainly can be made to do that, it will need some fairly careful crafting of the jaw in three-dimensions, or the purchase of a fairly expensive part from a chandlery.
But, as advertised, I'm a lazy, lazy cheapskate!