Were the writers wrong for having The Borg on an episode of Enterprise? I know they wanted to take advantage of The Borg's popularity as Star Trek villans to lure some viewers, but it didn't really fit. It was established in TNG that The Borg and Federation worlds hadn't come into contact. Wouldn't the records of Enterprise have been available to identify that they had been on a Federation vessel years earlier? Wouldn't Data have said, "An earlier ship called Enterprise captained by Jonathon Archer encountered a species that resembles The Borg on "such and such" stardate. They learned..."
The writers were perfectly within their rights to use the Borg in Enterprise. Regeneration
fit perfectly with the altered Borg timeline created by the movie First Contact