The lovers are much more interesting & a part of the story than the average polyamory romance story. The vampire angle is interesting, not quiet Space Vampires but absolutely in that direction. This is from a distortion of having read more than a few of books in this subgenre. It is much more satisfying than love triangles in teen angst dramas.
Obfuscating a much larger world would be nice. Logically with a population of a billion, Vearth will be seven times less populated as our planet. That is still a lot of space for animals to roam. Nature would be in the process of taking over abandoned human built structures... It happens a lot quicker than people seem to think.
Yet a billion people is still enough for myriad social strati beyond what the protagonist or his coven is aware. Actually having a segment of rogue humans rebuilding their civilizations in the caverns of Vearth's crust would be easy for a reader to accept. After all, politicians are lazy even if they are vampires.
Actually having super heroes/villains on Hearth would make the world more interesting. Why the group doesn't miniaturized the tech & then overhaul a mansion on Hearth is puzzling. It would protect their stock, as Hearth is made to appear as unaware of the reality of Vampires... hence less threat.
Storing living bodies in the middle of Vearth's New York seems to be a grossly unnecessary risk, given the cyberpunk description. A pillar of cyberpunk stories is the overreaching control of the Powers that Be. When our coven encounters that, it should be them facing the threat of violence by one of those PtBs.
The description of vampires is that they are biological. The more magical traits such as a lack of a beating heart should be taken out. Trying to do both just makes it fail at both. it's like trying to mix oil & water. the two natures separate themselves from each other. That doesn't affect whether or not there is magic in the world.
Would be interesting to me if the protagonist got his coven pregnant. That is where the urge to procreate comes from, & describing it as something that makes the protagonist unique would give Clementine a reason to be less violent when trying to deal with his family.
Hopefully Clementine will be more than just the sire of a rival family. Given the description of her money & resources it seems she should already be aware of both the protagonist & Hearth. History has shown plenty of examples of emergent technologies being invented simultaneously by scientists separate from each other. Altruism is great & noble but on the macro level Greed is a much more reliable motivator for new technological discoveries. So other groups discovering the tech on their own should be due to financial motivations.
Humans being thought of as a dying species on Vearth is described as public knowledge. If it is that widely known, then even more families than just Clementine would be seeking a solution to the problem. The description of animal blood removes it as a possible solution. The rich would never accept it as such.
Emergent advanced technology, punching holes in the fabric of space should do more & larger damage than simply opening a window. Other stories get by this by having the tech be "ancient relics", or gods, so someone or something else already minimized the damage.
It would be more interesting if Vearth is a larger planet than Hearth. Not terribly larger & a lower density could keep the gravity the same. There could be a couple continent sized geodes in the mantle like in the movie Core. It would give more space for plants & nature to throw problems at the vampire civilization.
Most important of all is both Vearth & Hearth need to change due to actions & choices by entities/groups beyond the awareness of even ninety-six percent of Vearth New York covens. Earth is a big place, & most stories seem to treat it as if it is a small city or at most a state. The trick to telling such a story is a matter of perspective, more specifically limiting the perspective to the protagonist's senses.
At least this is simply what is seen by me. For Gravity being shared by you, grateful am I. May the Goddess be asked to alighten a path towards love, joy , & happiness along the self'determined life'cycle chosen by the higher'self of yours by you, pray do I.