Make light marks on the stitched curved seam similar to the hours on a clock (we did ours in a light blue).
Using small sharp scissors, clip tiny V-shape wedges out of the seam allowance at the marks. Make clips close to, but not into, stitching.
Once the unit is turned right side out, the fabric of the seam allowance is reduced and the pressed edge is flat. That’s the look you want. Here, you can see the clipped seam inside this sheer fabric unit.
From the right side you can’t see the seam allowance, but you see the result of clipping a curved seam: a smooth and flat outer edge.