Yes, poncirus and some of its hybrids show a tolerance to the HLB infection.
linkThis tolerance is polygenic , that is requires a presence of several resistance genes, some of them diminish attack by psylids, while other are controlling the infection.
In SunDragon only some of these genes are present, so its resistance is lower than for the pure poncirus.
Still, this is quite remarkable achievement and probably a proof that cold hardiness trait can also be introduced to conventional citruses without a loss of fruit quality.