Upon seeing Trainz 2022 on sale today, I decided to buy it and give it a try. I was pleasantly surprised, as all of my current content works in this version of Trainz, with eye scripting and everything, without any modification needed on my part.
The irony is that these models are using an earlier version of the eye scripting. I did have an experimental version of Percy set up with the TTTELocomotive2020 script, however this version did not actually work - it didn't show any script controls, and didn't even take a driver.
As such, it seems that all the models on this website will work in Trainz 2022 without any modification. Thus, I've decided to switch to Trainz 2022.