What Bob and Aerodyne said.

Have seen and have done boom repairs with string, straight edges, jigs, laser levels and a few with mostly highly calibrated eyeballs doing the leveling. A correctly aligned fuselage is what matters, not how it got there.

Like Bob, I have observed some amazingly non-symmetrical factory-fresh gliders that went like hell and flew straight. I have also seen some that were dogs but why they were so poor could not be measured; everything spec'd out fine.

The structural integrity is difficult to discern without destructive measures. Given that, if it was done by someone reputable, has held up for XXX worth of flying, and the exterior and interior surfaces look OK to the eye of someone who knows what they are looking at, I would not worry for my safety.

Documentation is another matter. One would expect to see a 337 for Std Airworthiness ships and a sign-off by an A&P for EXP. All should have a new W/B. Given that, some of the best GlassGuys were among the worst at doing the paperwork.