Chempejak is an English name for crosses of jackfruit and chempedak. There are multiple varieties. Here in Hawaii we have Cheena (or CHNA, NA for Nangka = jackfruit), Nangkadak (introduced by Frankie Sekiya), and Sri Gading (introduced I think by Richard Campbell). I have these three growing and have tried and love the fruit of each of them. I rate Sri Gading as the best. I like them more than jackfruit but I think their fruit is more akin to chempedak and not so comparable to jackfruit. Seedlings of chempejak are highly variable but sometimes quite good.
Aloha, Steph