Thanks for the feedback - we're constantly updating the app;
RailModeller Pro and Express are currently at version 6.0.12 (with 6.0 released last January). However, we don't currently publish a dedicated post in our News section for each minor release so just looking at our News page might be a bit deceiving..
You can still see the entire update history for any app in the Mac App Store app.
We are currently putting the finishing touches on the 6.1 major update including new features like exporting layouts for use in the JMRI model railroad computer control system, new QuickFilters in the Track Catalog, redesigned and extended Community Layouts, support for negative heights, improvements to the 3D view and many other things.
All going well the public beta should start in a few weeks with the general public availability shortly thereafter!
Hope this helps,