I couldn't find the information on TRS22, so I'm going out on the assumption that it's the same at least for now since it's still in beta because the graphics requirements only list the minimum hardware.
If your current system supports TRS19, it'll run TRS22 fine if not even better with smoother graphics and overall better performance going by my experience so far.
As mentioned many times in the Trainz Newsletter and on the Trainz Plus site, DX12 will be added to Trainz Plus and possibly to TRS22 in the coming year. Tony says it is pretty much complete.