The Timeless Child doesn't make the real name concept any less valid. It's another layer to the identity mystery. We don't know the secret they kept. The fact that the Doctor has memories of a childhood shows this. But now they get to grapple with whether or not that's THE truth or just THEIR truth

Macchio actually did have experience in Karate though not to a competition level, the style he studied is very rigid and blunt, compared to Jeet Kun Do or Wushu it's visually boring is all

I honestly took that then and now as farm boy in over his own head trying to feign the legendary Jedi. If a good character writer had the reigns Luke could be a study of the chosen one narrative leading to overwhelming imposter syndrome

It's disingenuous to call tlj mis-characterization, the flaw is that there is nothing explaining the process of his changes, we're shown a 180 from the nostalgic view with no in-between demonstrating his fall. The time gap is plenty for such disillusionment to occur