Thanks for your response! Bapah Kadir is just someone with a collection of old Sajen who knew the archaeological source of each piece, and suggested that differentiation. I thought it worth mentioning for anyone who has some Sajen and knows where they came from, so that they could look for this inclination of the "head" and possibly verify or refute the notion.
As for princess Darawati, I thought that maybe if she was from Champa, we could then begin to see if certain motifs or items originating from Champa were introduced to Majapahit art at that time. Then we could look at the age of those forms, or otherwise to see if any of those forms survived within the region that Dongson daggers have been found between the time that they were produced and the 15th c. If we saw that there was an influence from Champa at that time, it might be a piece of the puzzle at least to discovering where the idea for the "sajen" began. Of course all of that might only be worth looking into if there were first some indication of interaction between the empires, e.g. intermarriage, and might be a bit of a waste of time if it turned out that what we thought was a royal connection was in fact just between south Sumatra and Majapahit. So for your consideration:
https://nusantarahistory.wordpress.com/tag/darawati/
https://nusantarahistory.wordpress.com/tag/darawati/