Hey guys,
Just want to share my experience today on changing language pack on my E72 NAM version.
Please be noticed phone flashing is at your own risk!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
OK! Let's start.........
My device: Nokia E72 NAM Black ( RM-529. model E72-2. Code:0591928 )
Current Running Version: 021.024
Language pack willing to change: E-72 Black (RM-530 )
(1) download the whole RM-529 firmware version 021.024 from NAVIFIRM to assigned folder named RM-529 and you should see below just like this after downloaded if you open the RM-529 folder.......
rm529_021.024_prd.core.fpsx
rm529_021.024_45.01_Americas_QW1_prd.rofs2.fpsx
rm529_021.024_244.02_NAM_US_prd.rofs3.fpsx
rm529_021.024_U000_850.000_prd.uda.fpsx
RM529_0591928_021.024_001.dcp
RM529_0591928_021.024_001.vpl
RM529_0591928_021.024_001_signature
(2) download language pack by chosing RM-530.--version 021.024--HONK KONG QW BLACK (0586202). Then select and download
rm530_021.024_38.01_China_QW2_prd.rofs2.fpsx
rm530_021.024_C00.01_DEFAULT_prd.rofs3.fpsx
(3) rename 2 files from (2) to replace 2 files to (1)
(4) run Phoneix, scan product to make sure your phone is coneected. Then open product to select RM-529.
(5) Hit flashing and firmware update then chose the folder RM-529.
(6) Hit refurbish......and done!
I 've doing this twice because at the first try, I only changed rofs2 file. Everthing went smooth and I got Chinese display and input.....BUT.....the build-in web broswer won't open ( as well as facebook, youtube...etc ). So I just did second try to replce both rofs2 & rofs3 files and PERFECT!!!!

Thanks to sonymd and tiunilohmu for some advice and sorry for my poor English.