I won't say I'm an expert on Palembang kerises, but being one of my favourite area of keris collecting, this keris blade here does not have the 'look and feel' of a Palembang keris. The luk and greneng, and the appearance of the metal, pamor do not look like Palembang.
You know i do agree with you Kai Wee which is why i posted my follow-up after further consideration, though it probably isn't Madura either.