You can copy your install folder to a new place and use that as your install/data folder for new versions. Makes it pretty quick, depending on how large your install folder is.
Like I said, I don’t think they have done any further optimizations. It was that version that we finally got Metal optimizations. I think they were able to do ASi so fast as they already had iPad and iPhone code.
Trainz has had Metal and ASi code since Trainz 19 SP3, however required Big Sur at a minimum since then. This did improve the frame rates. One thread at the beginning of ASi support. I don't think they have added further optimizations.
I think everything is really up in the air. I think bio or solar fuel as the direct replacement for fossil fuels for trains would be the best. Then they can refuse their existing setup and locomotives. Second best is all electric with utility scale battery backup, at least then depending trains...
Once you have imported your TransDEM route in to Trainz, then if you have plus, you can convert it to HD terrain format and manually apply more detail then.
Download the latest full installer, and install. I would not use the patch installer until after the full installer is done. Then point the user directory to the same directory if you want to keep what you have installed, or not if you want to test first. Then setup the patch stream how you want.
There is a few of us Mac people on here. Keep in mind, some routes are more demanding and will reduce the FPS. Depends on the number and how demanding each asset is.
I would just install using the latest installer to bypass that error and point to the user directory. I had that same error and posted about in the beta forum.