In HTM community repo, I saw the last commit for the numenta.app is like 3 years ago, does the newer version nupic still support nta.utils and htmengine?
Please open a issue on their issue page to ask the devs directly.
Yes, utils and engine exist although they have evolved somewhat.
The Network API as described in the Nupic documentation has changed very little. The calling arguments for the various algorithms has evolved somewhat to accommodate the SDR object for passing data rather than sparse arrays. More algorithms have been implemented in C++.
Please check the README.md
There is a CHANGE_LOG.md that describes deviations from the Nupic library. API_DIFFERENCES.md describes differences in algorithm calling arguments.