@Hepps Yes, though you are correct most of the improvements over the last year or 2 have been around AI, website, forum, map downloads, transport loading/unloading, territory name auto-placement, settings window, WaW, and technical changes (moving to github, build automation, refactoring, etc). For reference, the release notes (which definitely don't capture everything) are here: http://www.triplea-game.org/release_notes/
The "engine" and "features" are pretty broad topics. Are there specific threads you are referring to? Most of the engine work recently has mostly been bug fixes. I think many of the more complex features we already have also don't fully work in many cases.
I would be interested in what the community would like to see prioritized. Improving some of the existing features? Completely new features? UI improvements? AI improvements? New ladder? Certain bug fixes? Better map making tools?
We can either use this thread or create a new one to collect ideas then even consider a poll to vote on popularity. This is what I was doing with the AI for a while.