Well from what I know if you can find a way to export the model as an .OBJ file there’s an old conversion program that will automatically convert the model to they file types Train Fever uses. I only use Maya 2015 & 2016 so I can confirm it to work without any extra features.
You still need to make the .LUA, .MDL, etc files manually, but this also includes a tool to view the file without opening the game (assuming you can get it to work as all my PCs can’t open the viwer at all for some reason.)
Sadly the link to the download is long gone, but I still ahve the programs backed up, so if you want to try them just ask me.