I recommend running the test that kavadude linked you to when trying a new vendor, especially if the kava is very potent and cheap because tudei kava is very cheap to grow and offers a high yield in terms of biomass, potentcy, etc.
Regarding the cultivars, Melo Melo is apparently very rare, and very expensive kava at that. I've heard that those who grow it actually grow it in the middle of their plot "hidden" from others because it is so high rated that it is worth stealing and apparently this stealing isn't rare. Borogu is a common cultivar from Vanuatu.
I can't find anything in any of the documents or articles I have regarding a cultivar named "Plarasul"
The Codex on Kava Safety lists these as safe kava varieties from Vanuatu:
Palarasul, Palasa, Poivota, Pia, Puariki
And these are from the compilation of chemotypes (and I'm having source amnesia as to where it came from)
Palarasul Santo 246531
Palasa Santo 246531
Paliment Emae 426351
Could just be a misspelling or a miscommunication between the grower, wholesaler, exported and vendor. I'm guessing it's referring to Palarasul as that's a very similar name.