Some aspects of the game remain hidden and without more experimentation on the effects of playing with more advanced configurations within the game, there are still some aspects to modding that cannot be done and some that may perhaps never be possible.
GLOBALS EXML Files and Unknown Properties
The most game-changing attributes and structs are found in the GLOBALS EXML files that are all found in the root directory of a fully extracted game archive. These include everything from the physics values of spacecraft, the density of clouds and fog on planets, the way information is rendered in the HUD, and more.
While some of these values have already been exposed, many unknown properties remain as such as they do not have attached names to be found within the binary from which MBINCompiler obtains most structures for EXML files. There is currently *no way* to find out exactly what most of these properties are unless one is willing to test them manually by changing some values and spotting differences in-game.
Oddities Not Found in MBIN's
While spawning objects on planets have a wide variety of already-existing solutions, the ability to spawn new objects in space is locked within the game binaries rather than the MBIN files and thus cannot be changed without modifying the game executable itself.
Any form of functionality the game does not provide by default cannot be introduced without modifying the executable itself or inserting code via NMSE (script extender).
Things Requiring More Research
Custom animations are currently out of scope and is not yet supported by the model exporter. Translating Blender animation armatures into No Man's Sky's animation system is a difficult task and not yet doable.