So there were 2 layers of sponge with jelly in the middle? Sounds yummy.

I googled jello sponge cake and found some interesting options. One where you soak the bottom sponge layer in jelly, them cover with fruit before adding the top layer then refrigerating. One which was a layer of sponge, strawberry mousse then strawberry jelly - hmmm.

A tip i read was use less boiling water than normal. Once the crystals are dissolved add a cup of ice. Once the jelly is thick but not frozen, pour it over the sponge. Then refrigerate.

Let us know how you go.