Your seats are organized in sections as shown below, with seats in each section (branch of the data tree) in straight lines. No doubt deliberate and for good reason?
seats_sections_2020Sep12a.gh (166.7 KB)
But in case you want smoother alignment, I added a green group to rebuild the row curves using a curvature graph on the bottom row as a guide. I also added the orange group to apply the rounded Z values to the resulting seats, meaning all the seats in each row now have the same Z value (which is not the case in the points you supplied).
seats_2020Sep12c.gh (186.0 KB)