If you are asking what was added in that specific version of the game/SKSE, it included:
Generally stable, but highly version-dependent. It was specifically built for the "Anniversary Edition" update (1.6.342) and will not work with older or newer game executables. skse 16342
You have a mod that expects Skyrim version 1.6.640 (the latest AE) or 1.5.97 (the old SE). Fix: Use a tool called Address Library for SKSE Plugins . For version 1.6.342, you need the "AE" version of Address Library built specifically for 1.6.x (which includes 342). If you are asking what was added in