According to TCRF, some unused sprites of a "Flower House" (named similarly to other castle town buildings like the Church), and Christmas-decorated versions of buildings like Seam's shop, Party Dojo, Cafe, etc, are all in the files of Chapter 5. To me, this is very obviously content planned to be used for when Noelle enters Castle Town in Chapter 6. Is it worth noting, or too speculative? https://tcrf.net/Deltarune/Chapter_5/Unused_Graphics
It's possible they were meant for Chapter 5's credits.
This is true. But if they were, especially the "Flower House", will appear in Chapter 6, or at least an improved version of the sprite if the team isn't satisfied with them.
Actually, when I think about this, this is implausible. Because Kris has the "Ball of Junk", so the Flower Kingdom NPCs cannot have entered Castle Town alongside Susie. So unless Chapter 5 had a lot of cut ending content that was delayed to CH6, this is CH6 content leftover.