Since some point before 1.7 Spigot added a getLocale() method to Player that returns the player's current locale as String.

While I do not want to enforce Spigot for using MyWarp, MyWarp could use this method if it is available instead of using reflection to access the locale field within Minecraft's player object.

To use this method at compile time, mywarp-bukkit would need to be builded against Spigot directly. Then: player.getLocale().