Yes, they only go through to top layer, and they're mostly for decoration, although they do help the apron fall back into place when the breeze is done.

The way I deal with the wind, is to not worry if one apron blows to the side, because all that's going to show is a thigh, and most women are going to get the same thrill we do when we see a slit skirt blow to the side to show a lot of leg on them. Even with the narrow aprons of my Utilikilts the most that's going to show is the upper thigh; trust me I've worn them in an onshore breeze on Huntington Beach Pier; If the breeze is blowing one side open, it's likely holding the other side closed.