So, here you can find a simple tutorial to let your phone speak your mother language:
First, you have to install the Xiaomi MI4 WM 10 rom as per instructions provided here or in the international miui forum.
After the phone reboots the first time, dont't even choose the language and let it rest untouched until you have performed the following steps:
1) Download the language packages you will upload to the phone from the 10586.107 release here: http://forum.xda-developers.com/atta...7&d=1456506098 (open the .txt file and select the URLs of the files you need to download, copy them and paste the strings into your browser: it will start to download)
I downloaded the following files for the italian language (just search the relevant files for your own country: it-it is for Italy es-es for Spain, and so on):
You can skip the speech data and the keybord data cabs, as you can download them later on when you will configure the phone.
2) Put the 2 cabs you have downloaded in a directory (e.g. c:\cabs)
3) download the iutool package from here: http://forum.xda-developers.com/atta...2&d=1472659473 open the .zip file and click the .msi to install it on your PC
4) Open the file explorer on the PC and go to C:\Program Files (x86)\Windows Kits\10\Tools\bin\i386 . Right click holding down the shift key in an empty part of the window and choose to open a command window right there.
5) Now grab your phone, connect it to the PC via the USB cable, and inside the command window you opened on the PC, paste the following command: iutool -V -p pathtothefolderwiththetwocabs (e.g. c:\cabs as I suggested)
6) wait until the phone reboots and enjoy the Xiaomi Mi4 completely translated in your own language.
7) Configure your phone (download keyboard settings and speech settings for your country), then update the phone to the last available release (14393.67 at this time).