Maybe a wrong material settup in Kerkythea (Answer: No, bad topology)

[micheus]

Can you shared the .wings file for test, please?

here is it. I hope you get everything you need.
I didn't added thickness, so maybe you get that overlapping issue. But, there is a saved selection for the bottom faces, so it's easy you do that by using Inset [RMB] using small values for Distance and Bump (0.002 may be enough)

It would be better, to have hole from bottom side of leaf.
Because I assume, you used the "clip mapping" to cut the not modeled parts.

Just the mask for Clip mapping was required.
Although I had set it to the material it was not applied to the objects - that was the strange thing happen when everything I changed didn't make any difference. I just realize today that materials cannot be applied to a group in Kerkythea. I exported the leaves uncombined from Wings3D and trying to get some time in KT I stored the two materials used in the Library. After that I grouped the leaves (two groups) and all changes I did to materials I applied to the selected KT group. To me, it's a KT bug.


Something to further projects that uses transparency is take care about the resolution. Each leaf uses a 512x512 (1024 for the four leaves) and that cause we to see some aliased borders when increasing the image size for the render.