That's the problem, isn't it? Nobody who works on Python actually worked on this fork, but it sounds and looks official. That's why the Python Foundation people found this troublesome enough to demand a rename.

Tauthnon has lots of additions to normal Python, most stemming from a bunch of PEPs that author liked. You can't run Tauthon code on any Python interpreter (either 2.7 or 3.x), and there are a few edge case incompatibilities as well. It's probably a great interpreter for those who want newer features but are still stuck with Python 2.7 for whatever reason.