This one is a little hard because in English, that phrase would not be understood as affectionate or cute, unless you say it with affection. If you say it while referring to them fondly, it could be taken as affectionate or cute, which would be how you feel about them . If you say it with no expression at all, people would think that you just think the person you are talking about is stupid. Instead, you could say "That person is silly but cute" or "That person is ridiculous and sweet". This is how I normally translate "这人很二“, as long as they're not angry when they say it :)

"He is a silly willy". That sounds funny to me.

you are very two Sei molto due haha. 我乱写的，