The booster they test-launched used a hodgepodge of every engine that they’d built so far, with designs that were already obsolete when it was launched. It’s hardly surprising that some of them failed. The next test launch will be using a set of mass-produced engines with a more refined and consistent design, and they’re entirely removing the hydraulic system that was the cause of the first test launch’s failure.

Again, NASA is confident this will work out. The HLS contract is in the critical path for the Artemis Moon landing and they gave it to SpaceX in a form that depends on Superheavy working. This isn’t just my opinion here.