Python also suffers from such problems. For example, here’s scipy’s issue tracker, filtered for bugs only:

https://github.com/scipy/scipy/issues?q=is%3Aissue%20state%3...

Scrolling through this list, it’s clear that many are “correctness issues.”

I do not link this to argue that scipy bugs are more serious or more frequent. I don’t think that kind of statistical comparison is meaningful.

However, I think a motivated reasoner could write a very similar blog post to the OP, but about $arb_python_lib instead of $arb_julia_lib.

I suppose my position is closer to “only Kahan, Boyd and Higham write correct numerical algorithms” (a hyperbole, but illustrative of the difficulty level).