Of course, 12 years old is suitable for learning go, and there is nothing wrong with the chess I learned at 2 1 year old this year. The book guidebook is very good. I downloaded it from the internet. I suggest you have a look. However, Weiqi is still very complicated, which especially tests people's thinking ability. However, I think chess is also very good, the entry is relatively simple, but there are also many means of attack and defense. I hope your sister can get in touch with chess as well as Go. It's a pity that she has a high understanding and doesn't learn chess.

I hope my answer can help you _