After the error messages were added in 2.2 beta, I imported all of EDSM (~6 million star systems) using batches of about 500.000 stars, and that worked as intended, it just took a long time. However, this only covers systems reported by users of EDSM, and that is only a fraction of the player base. So this is no guarantee at all that you will only hit 'pristine' systems. Additionally, there are a lot of systems that are registered in EDSM but are still not tagged in-game because people simply bucky-balled/jonked through them. And last but not least, if a system is visited in beta, it will be added to EDSM, even if no player has ever been to the system in the real game.
So for the purpose of improving your chances on hitting 'pristine' systems, importing EDSM will most likely not have the result you want.