With the sales figures for the Trails series when we still had data from when Steamspy in early 2018, there was little reason to believe that Crossbell would be localized over more profitable games. Given that XSEED experienced layoffs after they lost the rights to continue localizing Falcom games, it would appear that they weren't making that much money off of those games after all. Obviously it would appear that the situation has changed with NISA's arrival. Perhaps NISA's marketing efforts has made the Trails series more popular in the West, and thus localizing the Crossbell games would be more profitable nowadays than back then. Alternatively, Falcom could be giving NISA a bigger cut of the share.
IIRC Trails from Zero was a website domain name that XSEED had registered in case they ever acquired the rights to the game. The Geofront team simply ran with it for their fan translation.
No way will NISA be using the Geofront's translation. There are far too many people involved in the creation of the Geofront TL to track them all down and get signatures from everyone. XSEED already learned their lesson with the Ys: the Oath in Felghana fiasco. That said, collaboration with the former XSEED translators would be nice for the sake of consistency, as NISA's terminology for CS3 and CS4 was inconsistent with previous entries in the series.