SX-1309 Fine Crystal Frost

I installed two precut window pane panels that you sent me last summer for my bathroom (which I adore by the way) and I'm wondering if I can also add Fine Crystal Frost in order to increase the privac

As long as the base film is smooth and not textured, it should work fine to put another layer on top. You could of course use it on the other side of the glass as well since that film is rated for both interior and exterior installs.