So I set about shortening it.
Because of the shape of the cutting component within the punch, it cuts the ends of the window before the middle section. It's therefore possible to position the window to one side of the sentiment and squeeze gently without cutting through the piece of card entirely.Here you can see that the card has only been punched at either end of the aperture.Now you can re-insert the card into the punch and move the sentiment along a little to centralise it, and aligning the previous cut, simply punch completely through the card. (Actually I don't take the card out, I did that just to show you what it looks like, but I simply move it along a little.)
As you can see from the card at the top, the tiny sentiment looks cute on its tiny mount!
I may try to do a video of this, but don't hold your breath!