But how? Does your C code compile to readable assembly? Does Haskell compile to readable C? The high level language is created because the lowlevel language is unreadable when solving problems the high level language solves.
While I agree with your premise, the thing that is driving the parent comment is the fact that when debugging a language such as Elm, there is no tooling to make sense of the output code. This forces the user to use standard JS debugging tools on a pile of JS that was not written to be debugged. This is a contrast to Java or C, where debugging tools and hooks have been built to indicate where the low-level code is mapped to high-level code.
At the end of the day this is more a call for language authors and the people around them to develop tools to debug the language.