Hullo Charles,
Nice piece!
I believe I may know the previous owner in Sarawak. Your piece looks identical to his, except his was missing the 3rd rotan binding (nearest the throat) and the middle binding was new. Also, his was uncleaned. He called his piece JIMPUL, early 20thC.
So, it looks like it may be down to a name-game.
Bottom line: It depends on faith, whether you follow the mainstream or a different school.
To me, it would be a JUMPUL; but then, I have other 'similar name' blade types: viz. JAMBUL, JEMPUL, and JIMPUL.
Best,