Summary of my idea:
Why? When you place a switch and tweak the length of the curve it also changes the straight part of it, this is kind of annoying when making inner/outer curve switches. We players can make use of these switches in a very realistic looking track.

How? In theory, having 2 options in the track blueprint GUI to change the curve length and the straight length
independently of each other would kind of solve this issue with the switches. Another idea to solve this is making a new type of switch with 2 curves instead of 1 and make them have differently (and independently) options for players to tweak, like orientation, length or vertical smoothing
Or maybe a GUI option to change the smoothing with custom curves, cause when trying to make custom switches the curve looks kind of... wrong?, let me explain with a photo...