Right now it is quite limited.
Arraying objects along path especially should enable:
-orientation lock to vertical or custom direction (for example: railing posts along 3d curves should remain vertical)
-arraying along path should enable planar rotation (or in any plane) according to guiding curve (for example light posts follow one curve but their orientation in plan should be perpendicular to some other curve)
Advanced arraying is essential and relevant for many aspects of modelling.
These things are easily achievable via visual scripting but GC is not available for basic MSTN but still could be covered by standard commands.