Seven can't have knowledge that the Borg would both succeed and fail at assimilating Earth.
Yes she can.
The enterprise took sensor readings of Earth when it was assimilated, just before they followed the Borg back.
The Borg came onto Voyager and assimilated engineering. They obviously got computer access, even if Data locked them out of some areas.
The Borg could have accessed those sensor logs.
The drones in the Sphere survived the fall to Earth relatively intact, as we know from Regeneration. They could have been sent those sensor logs after the Borg on the E accessed them.
The Borg on the planet are revived in Regeneration and at the end of the episode send a message to the Delta Quadrant.
The Borg in the 24th century receive this. Seven becomes aware of what happened, as do all the other drones. Also contained in the transmission is information about how humans were able to defeat the Borg on three occasions (the escape in Q Who, The Best of Both Worlds and the Battle of Sector 001 in FC). Unfortunately, some information is lost (the Borg in FC were trying to send an interplexed signal; in Regeneration they weren't able to do this, which is why the signal took so long to go to the Borg.)
The Queen sends the ship that attacked the outposts in The Neutral Zone. It finds that Humans are unremarkable and heads home. A waste to send Cubes across the galaxy to assimilate a species that is just like the ones in the DQ.
Q Who. The Cube on its way home finds the Enterprise, and the Queen becomes curious at how it escaped so easily. The Cube turns around and we see it again in BoBW.
Then another cube is sent, it gets to the Federation in FC. Launches a sphere, yadda yadda yadda, and the drones on board are given specific instructions by the Borg Queen that when you are revived by those scientists after being pulled out of the snow, make sure you send that information that originally got me interested in the Humans, okay?
Not canon, but it works.