HOW TO CHANGE INGAME UI LANGUAGE solution here

[Kamboyah]

In Steam Game Properties Settings find Advanced Launch Options and into the line simply add the command: -language italian , or -language english , or -language YOURLANGUAGE then save and exit. This overrides your Steam language and region setting.
shoutout to thread http://dev.dota2.com/showthread.php?t=131551 for solution,
shoutout to https://steamcommunity.com/app/570/discussions/0/598198356185542141/ if someone can please share there this solution. Some people still can't find it and it's here, working, thanks to the Source engine.