Einstein knew the works of Bach quite well too. That doesn't mean that Bach had anything meaningful to contribute to our understanding of the world (except insofar as figuring out how to write good music is such a contribution).
However, we are not talking about Bach, but about Einstein's knowledge of epistemology and that he certainly was well versed in that subject and didn't make such a basic mistake as you alluded to.
What I was alluding to was Einstein's belief that the EPR paradox was evidence that QM was incomplete. He was wrong about that, but can be forgiven because he didn't know about Bell and Aspect.
