I would like to know if they plan to add more races to the game type Yuki-onna or Oni if it's a lot of work you could always use the mods

Fairly sure there will be no more official races added to the game although there may be 'official' modded races if the mod section of this forum is an indication. And as iconic as Snow Maiden and Oni are in Japanese folklore, there's not that many art for them so adding them officially would be hard to find enough portray/fullbody images.