Hi Amuk. Why do you believe the hilt you have placed on this keris originated on the North Coast of Western Jawa? It clearly appears to be a coteng hilt.
Do you have some provenance for this assertion. Though i believe many people have traced the evolutionary origin of coteng and tajong hilts back to Jawa the primogenitor hilts that are usually pointed to are not the fully developed coteng or tajong forms. But if you could show evidence that such hilts did exist in Jawa back then you would have an important discovery.