The Chinese word for Huan is "番" (fan).
In ancient China, "番" is a derogatory term for anything foreign, uncivilized and barbaric. In fact, in ancient China, anything foreign was considered barbaric, because 2000 years ago, there weren't many advanced civilizations in the world, and China was the most advanced in this part of the world; the other advanced civilizations at that time being India and Rome in the Mediterranean.
Sweet Potato is 番薯 fan xu - can also mean Wild Potato. Sweet potato was considered poor man's food in ancient China.
Huan Na is the Hokkien word for 番儿. Maybe 儿 is not the word for Na but the meaning is the same. Na in Hokkien means "children". The full Hokkien word for children is "Gin Na".
In Teochew, it is Huan Kia, also 番儿. Teochew word for children is "Noon Kia".
The Cantonese call White man Low Fun - 老番.
In southern China today, some people still call foreigners 番客.
Older Chinese use the term Shua Huan - 山番 - meaning wild people of the hills.
When they saw the American Cowboys and Red Indians on TV, they called the Red Indians Shua Huan - 山番.
So Huan Na and Huan Kia actually mean barbaric children. Not very nice words.