Batiks have very little fraying with a blanket stitch edge. Cottons have a bit more fraying. How about satin stitching the appliqués down with a thread that matches the background? I use a stabilizer behind the background fabric when doing satin stitch to prevent tunneling.
How intricate are the appliqués? Can you do kind of an paint splotch background shape and use the dryer sheet or light inner facing method for them? You sew around the appliqué right side down to the light weight dryer sheet, cut a slit in the sheet and turn the appliqué right side out and it is ready to stitch down.