Do they sell Dango?

They do.

I went there once about 11 am, I did see Dango (Dango), they sell Daifuku (Daifuku).

Depends which store you visit. I find that the item selection changes often so I cannot say which one carries it anymore. Try the Rainbow store. The Henderson store has a small selection. Durango is mainly sushi and I never seen it at the Summerlin location.

Sometimes