What about adding a single function that would take 3D world (or construct) coordinates and project them into 2D screen coordinates? It would cover most use cases (AR HUDs, custom location markers), and would also be faster than doing 3D projection math in Lua.
Agreed. There are already at least 3 separate Lua APIs: 1) the control unit API, 2) the screen (render script) API, 3) the internal tutorial & achievement API. Adding one more (control unit API v2) shouldn't be impossible
For compatibility with existing scripts (and consistency with other core.getParent* functions), could core.getWorldVelocity() always return absolute linear velocity, and velocity relative to parent be returned by a new function core.getParentRelativeWorldVelocity()? Same for core.getVelocity().