The earlier "Original Canon Castlevania" had the virtue of leaving things up for interpretation. For example, Dracula was mentioned as having had "different names over the centuries" and being a sorcerer who "sould his soul to the Devil" in SotN and DC, respectively. Whether this was taken into consideration during LoI's storywriting or not, I don't know. But in retrospect, it clicks into place.
Also, compare Sara Trantoul's soul sacrifice to create VK to the ghost lady who warns Simon in SQ. Hell, even the Poltergeist King can be interpreted as a spirit inhabiting the whip. I like to think that while different CV teams understandably started contradicting each other when the storyline started expanding a little from the "hero clan of vampire hunters kill a resurrected Dracula because he is a bad guy" setting, they did have the details of the earlier games in mind.