It was really just another one of those Kamen Rider cash cow movies that ignored past settings and the official rules within each individual series. I will note though, the movie seems to establish that the world from Ataru (where Kamen Riders don't exist but are instead fictinal characters) somehow merged with the primary universe and stayed that way even after the end of the movie. The movie really doesn't explain anything about the whole parallel world junk or the time paradoxes, so I don't really know what to make of it. At least until future sequels make something out if it. None of the three original Time Jackers even appeared in the movie, which I found to be odd. Sorry this doesn't answer your question. I personally feel really tired with how the Kamen Rider series is milking the whole time space continuum thing.
The movie doesn't even explain clearly why Build still retains his memories as a Kamen Rider. Nor does it explain why he stiill retains the memories after beating Tid with Sento and the others.. Really, my advice is to not worry too much about its chronological settings until more sources pop up to explain it clear enough for a newbie.