The closest potential match is with Sabine Elisabeth Oelgard von Bassewitz, a writer rather than a composer.
From Google search; spots removed from background with Photoshop.
The center of Countess Sabine’s bodice is framed by prominent seams. The bodice is adorned with a lace bertha while the sleeves are decorated with lace engageantes.
Keywords: Drouais, Sabine von Bassewitz, Countess, German, wavy coiffure, scoop neckline, lace bertha, elbow length close sleeves, lace engageantes, brooch, wrap