By far the best Jak I ever ate was at Excalibur, and it was deep orangish-red. I don't know if it was the Dang Suriya/Red Morning, or the Excalibur Red, or the Cristela.
I have heard also of some trees sold as Cristela which ended up giving yellow-fleshed fruit.
I have heard of trees marked not-for-sale, intended to be kept for graftwood, having been sold anyway by salespersons.
This is something EVERYBODY wants to get figured out.
I am one of the persons who has grafted Jaks at Excalibur....
P.S. No such thing as Timor Red, but one with a similar-sounding name may be released eventually--- not easy to propagate.