You mean japanese? They do mix up r-l on pronunciations, but I rarely see a written r-l typo. Plus, it looks the HN title was manually typed, so it's unlikely you would mix up r-l with a reference text. Most importantly, the submitter is already too fluent to make that mistake, regardless of his native language is.
> I rarely see a written r-l typo
Anecdotally, I once saw a codebase littered with the variable "rambda".
"Once" still qualifies as rare. And are you sure it was really a typo, and not intentional or some foreign word?