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

[micheus]

No problem olve11

I got your point, but that is not the problem in this case - I want them.
The bottom faces are intentional as you can see the left columnin the texture image are assigned to them. This kind of object - a leaf - can usually has its botoom area with a different glossy, slightly "whited" color and more wrinkles/rugosity - things that I was playing with too.

It's probably a problem of topology that the Inset should fix as I already verified too - as recommended to povmaniac.

Get faces with inverted normal was something not expected - I didn't checked by myself yet, maybe tomorrow. An object with four vertices and two faces produce valid normals. I just tried the same with multiple ones.