Very interesting. I've personally never heard of kava being called "red" and "white". I wonder if they're referring to the waka and lawena.
AFAIK there are two Tongan cultivars with
kula in their names. I believe
kula means red (shortened/conversational form of
kulokula). There are also two cultivars with
hina in their names. I believe
hina means white (shortened form of
Hinehina). BKH sells (or used to sell) products called Kula and Leka Hina.
There's also a Fijian cultivar called
Damu, which means red. The stems are dark, smooth, and can be reddish/purplish. I wonder if it's the same cultivar as the one called
kula in Tonga.
KWK calls one of their products
Vula (white) and while this isn't the name of a cultivar, some Fijian light-skinned cultivars have
vula in their names (
Vula kasa balavu, Vula kasa leka, Dokobana vula).