Dear Detlef,
I will eat my hat if that wrongko isn't from Madura. Certainly not Cirebon. The style is ladrang and most ladrang wrongko's have that similar style and one has sometimes to look very careful to notice the differences between the regions.
In return I give you this link. Study, but above all, enjoy!!
http://www.vikingsword.com/vb/showth...hlight=wrongko