Hey, I play in KOR server because it has more events/patches and they are up to date. Also the English client has many bugs there (Gold bug, Legendary bug and many). But in Korean server everything is good.I have tried this too, and it looks like the decryptor does not contain the correct key to decrypt several of these files. Although it does decrypt the .ini file perfectly. You may try to play along with the Notepad++ charset to utf-8 or Latin but i'm not certain that may change anything at all.
NB:
May I ask why you try to translate the KOR client while the EN client/srv shared here is working perfectly?
So coming to the topic, i contacted the programmer of the decrypt tool (Atom0s) yesterday. I reached to a point to prove that they key didn't change using a trick.
I decrypted the .u file and then took the result and encrypt it back. I pasted the final output file to the game folder and it worker perfectly as it's the original file! If the key is changed, then it won't generate the right file.
About notepad++, i spent whole night trying to manipulate the file but no progress.
Thank you :D