LEd

The Lightweight Locale Editor (LEd) allows to comfortably edit locale information files and locale definition tables.

LEd is part of the robbiblubber.org Utility package (https://bitbucket.org/robbiblubber/robbiblubber.util.NET/).
You can download the installer from http://instll.robbiblubber.org/Robbiblubber.Util.NET/instll.exe.