According to the credits for Before Meteor it seems Soken scored a number of tracks for 1.0 even before Tanaka's departure from the development team and Yoshi taking over (March of the Moogles, a track that played during a cutscene in the original Gridanian storyline, was one of them), and that is not including the tracks Ryo Yamazaki also supplied, although to be fair those were added after the staff change in the development team.

But you are right about Soken being the main staff composer - Uematsu's contributions were done under contract, given the fact he's no longer directly employed by SE and is a freelance composer.