These don’t show up in the “add context menu” (when I right click and search). I assume that these should come from Niagara because when I search through the code base there are matching names in some of the Niagara source files (eg. ExecutionIndexToUnitFunctionName in NiagaraDataInterfaceRW.h).
The same thing holds for the Elevation scratch pad.
The procedural foliage was designed for 4.26. I haven’t had a chance to revisit it in depth, but last I checked 4.27 seems to have removed or changed some of the functions that this tutorial depends on. If possible, I’d recommend following the tutorial in UE 4.26.