Steps to reproduce:
1 Create new user account
2 Select English locale
3 Login as new user
4 Look at directories in ${HOME}:
  ls -1 ${HOME}
  copy some files to one of folder, say Music.
5 Login as same user, but in different locale now, say French.
6 Run the command:
  ls ${HOME}

Expected result:
The folder name can be changed and updated according current locale.

Actual result:
The Music folder name will not be updated according to current locale. System will make another music folder with French folder name "Musique". This bug can be reproduced if the folder is not an empty folder. 

This looks not a good solution. Usually, people will copy files to these folders, if there are files, xdg-user-dir-gtk will not refresh the folder name. The result will be many folders with many locales in user's home directory. And it will make it hard to manage user's files. What if one user wants to manage all the mp3 files in his home directory? To import every "music" folder with different locale in my media player?