Seven can't have knowledge that the Borg would both succeed and fail at assimilating Earth. Therefore I propose that it cannot be a predestination paradox. The timeline where the Borg succeeded was erased when the Ent-E stopped the Borg in the past. Seven wasn't present during the events of FC and at the time (1999 Relativity's airdate) ENT the series hadn't even been conceived. As someone else said, "Regeneration" fixes this gaffe with the Borg sending a signal to the DQ.
Without that episode though you could watch "FC" and then "Relativity" and end up scratching your head thinking: "hey wait, Picard and Worf destroyed the dish before the Borg could send a signal in FC. How does Seven have any info about the mission to assimilate Earth if there was never a message sent?".
Seven only knew about the failed attempt to stop Zefram Cochrane's warp fight in "Year of Hell" ("The name of the ship was 'The Phoenix' [...] the Borg were present during those events"), and she learned the whole Pogo Paradox story in "Relativity" from studying the 29th century computer files of the USS Relativity prior to going back in time to stop Mad Braxton. In the 29th century, they scan time as easily as the 24th century Starfleet scan space - they would know exactly what happened.
I don't think the events of FC fit the role of a predestination/pogo paradox for different reasons. To me if you watch the series of events in FC. There is only one timeline that is constantly being changed and rewritten.
Unaltered which is supplanted by the Borg's incursion
Borg timeline: supplanted by the Ent-E
Final timeline at the end of the movie would be similar to Unaltered timeline with variations.
With Seven and the Temporal Starfleet guy fail to mention is that had the Borg never tried to assimilate Earth in 2063; Zefram Cochrane would've carried out his scheduled flight on time and first contact with the Vulcans would've still happened. The Borg's interference was not a necessary contribution in order to make first contact and by extension the Federation happen.
Not necessarily. Has the Borg not attacked, Cochrane's flight may have occurred earlier (remember, the TNG crew were working to the date they knew from the time loop, not that of an unspoiled timeline), the Vulcan survey ship misses them and things evolve very very differently.
Sometimes I wish ENT was officially made AU like JJTrek. Then they could've made it as futuristic as possible and not have to worry about why tech and story don't line up completely symmetrical with TOS and the TNG era. Rick Berman said in interviews after ENT was cancelled that was one of his ideas. To make a show that looked like it was 150 years more advanced that what we have now. Worrying about the prequel looking for advanced that tech and computers scene in TOS-TNG-DS9-VOY. ARGH THOSE HIDEOUS BLOCK COMPUTERS!!
I think people worry too much about how things look. It's no different to recasting a character IMO. Enterprise was pretty much it's own thing, visually - they snuck in some neat visual homages to other Treks but they clearly looked ahead of their present over TOS' 1960's-style past.