For the CORE, for the TW App (TW5), its mentored & led by Jeremy Ruston. He has strong focus on backwards compatibility.
There are many participants who write, contribute and critique the core there. Its rigorously compliant.
For everything beyond that ... many add-ons and so on---its a Darwinian System.
Folk announce stuff here in this group ... it has no standards as such, but generally it works out pretty well.
A MAJOR issue for a starter is FINDING things they need.
Often there is a solution but it lies buried somewhere in this group.
Getting good at searching this group is a very good idea.
Best wishes
TT