I think we can be sure that this particular hilt is collected in Cirebon but as Alan suggested, it might be coming from somewhere else even it is equally possible to be made over there. Banyumas is notable for their silverwork? keris perabot so that might be highly possible as well. The western approximate of modern day Central Java has both influences from Javanese/Sundanese culture. I attached a map so those who isn't familiar with the region might understand what we are talking in here. The question is then once Sunda region is Islamized, what hilt are they wear at wedding and other ceremonies? Raksasa hilt? not likely. Stylized hilt? Maybe, in the 17-19 c. They might keep it as pusaka, or still being made as personal keris hilt, but for public gathering? Those KILTV photos shows a little how nunggak semi hilt is popular in Sunda as early as 19 c. Detlef, I must say I'm not sure where it is made, it might be as far as Banten to Surakarta, so I'm sorry you might consider to change the hilt naming once again
Don't forget we have pesisiran Jawa Demam examples as well as Bebondolan and its old style wide gayaman, so influences stretch from Sumatra to Bali; so what make Central Java influence not possible in this case.
I don't know how to put it in English but:
Sometime unavailability is not because it is not existed but because it is not know
my two cents opinion
