When I first installed Winhttrack, my language preference is set to unknown
language to me.  To change Language Preference in winhttrack, 
1. you open up winhttrack, 
2. select the second top bar menu from the right 
3. select the last entry of the second top bar pull down menu.
4. it will pop out a window and at the bottom of that window, you can select
the language preference of your choice.
5. restart winhttrack and it will show your language of your choice.

Hope this help.