Regenerated the street blend from OSM and the DEM (the code was already correct: 279.6 m centreline,
saved clean) and sampled both surfaces at the player's X in metres:
Road_Hollywood y -9.0..-9.1, z 0.87..0.94
Sidewalk_North y +11.9..+12.0, z 1.51..1.59
The road is the south band at about 0.9 m and the north sidewalk is about 1.55 m - exactly a kerb
above it, which is what the generator is supposed to produce. The source is correct.
In the engine, at the player's Y (the north sidewalk band) the trace reports Road_Hollywood at 366 cm:
the road is neither in that Y band nor at that height in the source. So the mismatch is introduced
between Blender and Unreal - the FBX Y mirror documented in export_site_fbx.py, or the importer's
transform - not by the geometry or the placement code.
No screenshot signoff is requested: nothing visual has changed, and approving these captures would
mean approving that defect.