Cayden video tutorials are pack full of good information but they will make your eyes glaze over while watching all of them. He uses pay ware tools and Blender addons to do what he does. Most newer potential content creators will never go down that road to learn how to make content like that. The Trainz creating process is very involved now and most people are still creating their content in older versions of Trainz. As much as I want to make new PBR content, It's simply not worth all the effort anymore.
As a new content creator, with no reference to how content was made before TRS19, I can say Blender can appear overwhelming at first but it will become easier with time. Cayden’s “Blender for Trainz “ is great for learning only what you need to know about Blender to get assets built. If you want to create your own assets, it’s worth the effort.
And now for a word from an orphan in the creation world, an program that used to be included with Trainz for free - GMax. The baby brother of the professional 3d Studio, it is a simpler 3d modelling program that is easy to use and is still good for making backgrounds and distant buildings and when wrapped in Trainz Asset Creation Studio, exports IM files directly for Trainz. If you add some bump mapped textures, they can look pretty good too. It's still freely available around the Internet.
If you have ambitions of eventually making more sophisticated objects, I would skip GMax and go for more modern programs.