I see HKali as a pretty good sub for those who don't have DKali. It's another LKali but just dark and light, which plays pretty well with the ideal LKali or Ra team. But, she is a bit on the niche and the nice-to-have side, and that's from her rareness. And she is devil, which borks Sun Quan's skill, but does fine with devil-type color list, something that makes her quite niche. That is not to mention she is not as practical as DKali's 6x and heal with the active, and LKali's 1.2x for 6 combos, something that can be mastered with 3 time extends and a bit of practice.
Overall, she's definitely a whale, a supreme card to have. Her devil type makes her special and way more versatile. But at the same time, her leader, type, and skills make her quite hard to fit in to more traditional teams. It makes her kinda a hard choice to buy or not, since you have the choice to trade off between usability and versatility, both at very low low difference in case of HKali.
So the choice of grabbing her actually depends on the player: whether they have the composition for it and whether they are willing to pay for it.