I think only a few characters go to unique places and the rest simply return to where you recruited them. Yeah, Cross' cast feel very detached from the plot overall, with only a few exceptions. If Cross ever got a remake treatment, and it should, I would like Kato and the team to come back in and probably relegate half the cast to NPC status and then add some scenarios to make the other half feel more prominent in the plot. Adding some more Dual and Triple Techs would be a must as well cause there is so much potential for pairings.

I think it would also be cool if a remake added two new dungeons that involve entering some other alternate realities. Like one based closer onto Radical Dreamers and then maybe the Reptite dimension would be cool as well. I mean the DS version of Trigger added two new dungeons so why not Cross?

As for Balthazar, it's only really a plot twist if you have never played Trigger. I remember spotting him on my first playthrough and after getting over the shock of him being alive, realized that trout was about to go down.