Err... actually Paradise Island is in the Carribbean, several thousand years removed from modern things, and it's implied that in the DCnU she's pretty much being kept in the psuedo-custody of the US military so, no, she might not actually know what ice cream is. This is pretty much the first time she's interacted with regular people.

Plus the stilted dialogue is because she' only just arrived in "Man's World".

I think that it's oddly sweet, like she's a DnD character that has appeared in modern day Washington and is asking the town's folk if there are monsters to slay.