Just about all of the problem with this is the way that BVE is coded as a whole. This is because Mackoy chose to implement various new functions into BVE 4 which were not present/ differently implemented in BVE 2. In some cases, this would mean the re-writing of large sections of code simply to achieve scenic parity. The best example of this off the top of my head is the way that panels & train acceleration work in BVE 4 as opposed to 2- in BVE 4, the .dll file handles most of these functions, & can be customised nearly at will. BVE 2 on the other hand works within a very restricted set of parameters, and workarounds had to be found to create effects. Therefore, it is easier in many ways to create the same effect in BVE 4.
Chris Lees