repair generated terrain seams

tests/generated_world_runtime_validation.gd

@@ -872,7 +872,7 @@ func _validate_elevated_cliff_feature(
 		var overlay_mesh := TerrainChunkAnalyzer.find_primary_mesh(
 			overlay,
 			(
-				&"chunk_0015"
+				&"chunk_0010"
 				if stable_id in [
 					&"chunk_9999",
 					&"chunk_9998",

tests/terrain_chunk_generator_validation.gd

@@ -629,13 +629,14 @@ func _validate_catalog() -> void:
 		]:
 			_check(
 				transition.overlay_only
+				and transition.primary_mesh_name == &"chunk_0010"
 				and transition.base_layer_scene != null
 				and transition.base_layer_mesh_name == &"chunk_0007"
 				and not transition.must_be_interior
 				and transition.prefers_map_boundary
 				and "transition" in transition.tags,
 				(
-					"Each raised-coast endpoint must layer the deep corner "
+					"Each raised-coast endpoint must layer the inland corner "
 					+ "over an authored level-one coastline."
 				),
 			)
@@ -657,6 +658,7 @@ func _validate_catalog() -> void:
 		]:
 			_check(
 				transition.overlay_only
+				and transition.primary_mesh_name == &"chunk_0010"
 				and transition.base_layer_scene != null
 				and transition.base_layer_mesh_name == &"chunk_0008"
 				and not transition.must_be_interior