I think pretty much everyone still accepts Kuuga and Agito as one world despite that contradiction.
When it comes to Kamen Rider continuity, where they don't always get a single show's own self-continuity straight, little details like when or how long need to be ignored for the bigger picture when it comes to explicitly shown/stated continuity between series.
This is why I think more people need to start accepting Den-o/Kiva as also being one world.
That is not correct. "Den" (電) does in fact mean "electric"
"Densha" is created when you combine the above kanji with 車, which can basically be translated into "veichle", "car" etc.