感謝 realfun 同學熱心幫忙，之前Bluehost +Wordpress 多國語系檔出不來的問題，Bluehost 終於有提供解法，供大家做參考。
以下是轉載兩遍後，Bluehost 的回覆:
I am sorry but we can not provide support for third party programs. This is a wordpress bug, I suggest you contact work press about help with their product.
Please be aware that we can not normally provide support for a 3rd party program, however I have seen this issue before with wordpress and it may help you to know this is a bug with their MAGIC1 and MAGIC2 variables in the/wp-includes/gettext.php file. You are using a custom install of workpress so I can not say this will solve the issue for sure, but replacing the $MAGIC1 line with:
$MAGIC1 = 2500072158;
and the $MAGIC2 line with:
$MAGIC2 = 3725722773;
希望以上資訊對有Host 在bluehost 的朋友有幫助。