I believe these to be fantasy pieces as none, to my knowledge have been dug in any of the areas of Irish Brigade action. There are no pictures of these devices on caps, though there are two very obscure examples of harp insignia. One is a shako cap plate from 1837 for the Boston Montgomery Guard, the other is an officer's private purchase embroidered green badge for a slouch hat.
I put these in the same category as the CS box plate.