Could it be a problem of localization?  Every language has its own sorting rules and often this is implemented in the library.  Maybe if you have japanese localization the list is sorted correctly.

Looking into the official bip39 wordlists it seems other languages have the same problem, e.g., french:


I'm not sure what the right solution is.  Sorting the word list with LANG=C would change the indices of the words and break compatibility.  Requiring that localization setting must match the language of the word list make automatic tests difficult.  Especially if you don't have support for the language installed.