I often had a problem regarding sponge cake-like batter. Namely: the edges looked ugly. :) The batter wouldn't exactly take the shape of the mold, because baking paper was too strong compared to it.
Then I learned it from my mother, that I was doing it all wrong...
Let's take the mold apart and cover the edges separately. Cut a piece of baking paper that is a bit bigger than the bottom of the mold. Cover the bottom (inside!) and fold back the exceeding parts.
Cut some smaller stripes from the paper. Now cover the side part from the inside and fold back the excess around the edges. If you make a flat cake layer in it, the stripes do not have to exceed the side part on both edges, just at the bottom.
When the side is fully covered, take both parts and assemble the mold again. Fold back the bottom excess of the paper, so it will prevent the batter from leaking right into your oven. :) It's ready. Let there be sponge cake!