To go back to the subject 

I checked with some friends (4x2) who bought Divinity by pack (1 + 1 Gift) : 
All Owners can change the language and all dudes with gifts can't.I think we found something weird with Steam/Larian.
@Lar_q / Raze :  can you forward this info to the dev team plz ?
Thx a lot,
Mae.
Your English is pretty good.  At the very least a lot better than my Russian.  I don't think I know a single word in Russian so I have to admire the people that can speak multiple languages. 
 Thank a lot you for your compliments, but I'm not Russian but French (in Canada) 

But yes, it's not always easy to me to speak/write a good English,
and for a game like D::OS with a lot of text I prefer play in my native language 

Mae.